DR.  ROBERT   KOCH 


Who  discovered  the  germ  of  tuberculosis  which  kills  over  four  hundred 
people  daily  in  the  United  States. 


THE    HUMAN    BODY 

AND 

HEALTH 


A  TEXT-BOOK    OF    ESSENTIAL    AXATOMY, 

APPLIED  PHYSIOLOGY,   AND 

PRACTICAL   HYGIENE 


BY 


ALVIN  EJAVISON,  M.S.,  A.M.,  PH.D. 

PROFESSOR    OF    BIOLOGY    IN    LAFAYETTE    COLLEGE 


ADVANCED 


NEW  YORK  .:•  CINCINNATI  •:•  CHICAGO 

AMERICAN    BOOK    COMPANY 


3>. 


BIOLOGY 

LIBRARY 

G 


COPYRIGHT,  1908,  BY 

ALVIN  DAVISON. 

ENTERED  AT  STATIONERS'  HALL,  LONDON. 


HTTMAN   BODY,   ADV. 

w.  P.  13 


Lib. 


*-" 


PREFACE 

THE  most  noted  of  England's  prime  ministers  said,  "The 
first  duty  of  the  statesman  is  the  health  of  the  people."  One 
of  our  own  statesmen  asserts  that  the  greatest  asset  of  this 
nation  is  the  health  of  its  citizens.  Inasmuch  as  recent  science 
has  shown  clearly  the  cause  and  prevention  of  many  diseases, 
it  is  important  that  this  knowledge  should  form  a  part  of  every 
individual's  equipment  for  the  duties  of  life.  The  greatest 
enemies  of  the  human  race  are  microbes,  which  annually  lay 
prostrate  in  this  country  and  Europe  seventy  million  people, 
of  whom  three  million  die.  The  microbes  feeding  on  human 
blood  have  caused  the  destruction  of  armies  and  the  downfall 
of  a  nation.  On  this  account  a  knowledge  of  these  infinitely 
small  forms  of  life  is  of  vast  importance. 

Since  the  foundation  of  many  diseases  is  laid  during  child- 
hood, and  since  new  ideas  are  accepted  most  readily  in  youth, 
every  boy  and  girl  during  school  years  should  be  carefully 
and  thoroughly  instructed  as  to  the  cause  of  human  wretched- 
ness and  the  means  of  preventing  it.  The  numerous  text- 
books on  elementary  physiology  have  largely  neglected  tbs 
discussion  of  facts  relating  to  public  health.  As  a  result  not 
one  in  a  hundred  graduates  of  our  public  schools  could  state 
any  evidence  showing  whether  vaccination  is  beneficial  or 
harmful,  or  describe  how  malaria,  diphtheria,  and  yellow  fever 
are  acquired,  and  how  they  may  be  prevented. 

The  pupils  have  spent  much  time  in  learning  meaningless 
words,  but  when  information  is  sought  concerning  the  evidence 
that  typhoid  fever  is  caused  by  drinking  polluted  water  they 
remain  silent.  A  pupil  is  rarely  found  who  can  state  clearly 
how  the  fact  has  been  established  that  bacteria  produce  dis- 

5 

255758 


O  PREFACE 

ease.  In  consequence  very  many  do  not  yet  believe  that 
disease  is  preventable,  and  so  pay  little  heed  to  the  laws  made 
by  the  state  for  the  welfare  of  its  people. 

The  facts  that  in  this  country  nearly  one  hundred  persons 
die  daily  of  typhoid  fever  and  four  times  as  many  from  tuber- 
culosis, and  that  these  diseases  are  largely  preventable,  are 
unknown  to  most  public  school  pupils.  As  a  result  the  people 
continue  to  use  bad  air,  bad  water,  and  bad  food.  Holmes 
wrote  fifty  years  in.  advance  of  his  age :  — 

"  God  gave  his  creatures  light  and  air 
And  water  open  to  the  skies  ; 
Man  locks  him  in  a  stifling  lair 
And  wonders  why  his  brother  dies." 

This  book  contains  a  sufficient  amount  of  anatomy  to  enable 
the  pupil  to  understand  the  physiology  upon  which  is  based 
much  of  the  hygiene.  Numerous  original  diagrams,  drawings, 
and  halftones  from  photographs  have  been  introduced  to  im- 
press upon  the  learners  the  most  important  truths  relating  to 
the  human  machine.  For  many  of  the  drawings,  I  am  in- 
debted to  Professor  W.  H.  Reese  of  Muhlenberg  College. 

A  considerable  number  of  pages  have  been  given  to  a  dis- 
cussion of  the  effects  of  alcohol  on  human  society,  showing 
that  its  power  for  evil  is  far  more  marked  in  producing  poverty 
and  crime  than  in  wrecking  the  physical  health. 

That  a  knowledge  of  practical  hygiene  does  prevent  waste 
of  life,  is  shown  by  the  fact  that  the  death  rate  per  thousand 
declined  from  thirty  in  1870  to  less  than  nineteen  in  1905. 
Diphtheria,  tuberculosis,  yellow  fever,  and  malaria  claim  fewer 
victims  every  decade,  and  when  knowledge  such  as  these  pages 
afford  reaches  all  our  citizens,  the  vital  records  will  show  a 
still  more  rapid  decrease  in  the  death  rate. 


CONTENTS 


CHAPTER  PAGE 

I.     INTRODUCTION 9 

II.     PLAN  OK  THE  Boi»v    . .14 

III.  COMPOSITION  OF  TIII-:  BODY 22 

IV.  LIFE  PROCESSES 28 

V.     FOOD  AND  ITS  USES 35 

VI.     MICROBES  AND  MOLDS .46 

VII.     MILK 54 

VIII.  NARCOTICS  AND  STIMULANTS        .                  ....       68 

IX.     THE  DIGESTIVE  SYSTEM 76 

X.     How  FOOD  is  DIGESTED 90 

XI.     THE  BLOOD 106 

XII.     THE  CIRCULATORY  SYSTEM 114 

XIII.  THE  RESPIRATORY  SYSTEM 132 

XIV.  AIR  AND  HEALTH 151 

XV.  ALCOHOLIC  DRINKS  AND  THEIR   EFFECT   ON  THE  HUMAN 

RACE 163 

XVI.     THE  EXCRETORY  SYSTEM .175 

XVII.     THE  OSSEOUS  SYSTEM  OR  BONES 191 

XVIII.     THE  MUSCULAR  SYSTEM 203 

XIX.  How  THE  NERVOUS  SYSTEM  is  CONSTRUCTED    .         .         .     215 

XX.     How  THE  NERVOUS  SYSTEM  WORKS 225 

XXI.     THE  SENSE  ORGANS 237 

XXII.     THE  SENSE  ORGANS  (Continued) 246 

7 


CONTENTS 


CHAPTER 

XXIII.  THE  CAUSE  OF  DISEASE      .         .         .....  259 

XXIV.  THE  PREVENTION  OF  DISEASE     ......  272 

XXV.     ACCIDENTS  AND  EMERGENCIES    .......  294 

PRONUNCIATION  AND  EXPLANATION  OF  DIFFICULT  WORDS      .         .  307 

INDEX         .  .  .  .        .  315 


THE    HUMAN    BODY    AND    HEALTH 

I.   INTRODUCTION 

The  Meaning  of  Anatomy.  —  The  science  of  anatomy  de- 
scribes the  parts  and  structure  of  the  body.  It  teaches 
the  relative  locations  of  the  many  organs,  such  as  the  heart, 
lungs,  and  liver.  Without  a  knowledge  of  anatomy  it 
would  be  impossible  to  understand  the  operation  of  the 
human  machine.  Ignorance  of  its  operation  prevents 
the  proper  management,  protection,  and  care  necessary 
to  health.  Health  is  wealth,  and  the  lack  of  health  is 
responsible  for  much  human  misery.  An  understanding 
of  the  parts  of  the  body  concerned  in  the  preparation  of 
the  food,  of  the  vessels  conveying  it  through  the  body, 
and  of  the  structures  for  admitting  air  and  getting  rid  of 
waste  materials,  may  be  a  great  aid  to  human  happiness. 

The  Meaning  of  Physiology.  — This  science  tells  the 
function,  or  use,  of  each  part  of  the  human  machine.  It 
explains  how  the  food  eaten  is  used  to  build  up  muscles, 
bones,  and  brain,  and  how  the  nerves,  heart,  and  blood  per- 
form their  duties.  The  study  of  physiology  helps  one  to 
understand  the  necessity  of  chewing  food  thoroughly,  by 
what  means  the  food  is  taken  from  the  alimentary  canal 
to  the  head,  arms,  and  legs,  and  how  the  brain  causes  the 
body  to  move.  It  shows  how  the  lifeless  bread,  meat,  and 
milk  may  become  a  part  of  the  living  human  body,  and 

9 


10  INTRODUCTION 

how  potatoes,  oatmeal,  or  fat  meat  when  eaten  may  help 
to  keep  a  person  warm. 

Importance  of  studying  Physiology.  —  Knowing  how  the 
stomach  and  intestines  act  in  making  the  food  into  a 
solution  to  be  received  by  the  blood  has  resulted  in  finding 
out  the  causes  of  dyspepsia,  and  also  how  to  prevent  it 
and  how  to  cure  it.  The  discovery  of  the  fact  that  the 
germs  in  old  or  unclean  milk  often  cause  disease  and  death 
among  infants,  has  made  it  possible  to  prevent  much 
suffering  and  to  save  many  lives.  Until  the  real  use  of 
the  blood  was  understood,  patients  suffering  from  various 
ailments  were  bled  in  order  to  remove  the  supposedly 
bad  humors  from  the  body. 

Prior  to  the  Revolutionary  War  the  insane  were  com- 
monly thrust  into  sunless  dungeons,  and  chained  to  the 
walls  with  iron  bands  riveted  about  the  waist  or  neck 
because  they  were  thought  to  be  demons.  Since  physiology 
has  shown  the  relation  of  the  mind  to  the  brain  and  the 
influence  of  health  upon  the  brain,  the  insane  have  been 
cared  for  in  a  more  humane  manner.  As  a  result  very 
many  recover  their  health  and  are  restored  to  their  friends. 
It  is  only  by  a  clear  understanding  of  the  actions  of  the 
various  organs  that  one  can  know  when  they  are  out  of 
working  order  and  the  kind  of  remedy  to  be  applied  to 
cure  the  sickness.  The  prevention  of  sickness  is,  how- 
ever, far  more  important  than  curing  it.  The  greatest  bene- 
fit, therefore,  derived  from  the  study  of  physiology  is  the 
information  which  enables  us  to  understand  hygiene. 

The  Meaning  of  Hygiene.  — The  science  of  hygiene  shows 
how  one  should  live  in  order  to  keep  the  body  in  a  healthy 
state.  It  explains  how  any  one  may  avoid  taking  cold,  and 


IMPOUTANCE    OF    STUDYING     HYGIENE  11 

how  to  avoid  such  diseases  as  yellow  fever,  typhoid  fever, 
tuberculosis,  and  malaria.  It  teaches  what  to  do  in  case  of 
an  injury  to  the  body,  such  as  the  breaking  of  a  leg  or  the 
cutting  of  a  blood  vessel.  The  success  of  the  Japanese 
army  in  the  late  Russo-Japanese  War  was  in  part  due  to 
the  strict  observance  of  the  laws  of  hygiene  by  the 
soldiers  and  officers  of  Japan.  Army  physicians  declare 
that  in  most  wars  before  the  present  century,  negligence 
in  regard  to  the  laws  of  hygiene  resulted  in  more  deaths 
than  were  caused  by  the  bullets  of  the  opposing  army. 

Importance  of  studying  Hygiene.  —  A  sound  body  is  a 
fortune.  Sickness  is  expensive.  Knowing  how  to  pre- 
vent illness  is  worth  more  than  knowing  how  to  cure  it* 
Before  1796,  smallpox  was  the  most  dreaded  and  the  com- 
monest of  all  diseases.  In  cities  having  a  population 
of  100,000,  more  than  2000  cases  of  smallpox  occurred 
every  year,  resulting  in  hundreds  of  deaths.  Some  cities 
suffered  from  much  more  severe  epidemics.  In  1721, 
Boston,  with  a  population  of  11,000,  had  5989  cases  of 
smallpox.  Eighteen  thousand  people  died  of  this  disease 
in  Iceland  during  the  years  1707-1709.  This  pest,  which 
once  was  a  great  affliction  to  the  civilized  world,  has  now 
become  almost  unknown  in  many  regions,  owing  to  vacci- 
nation. About  one  fourth  of  all  children  born  die  in  a 
few  months.  This  is  due  largely  to  ignorance  and  care- 
lessness concerning  hygiene,  on  the  part  of  the  parents. 

Recent  investigations  indicate  that  one  half  of  the 
1,000,000  people  who  died  of  tuberculosis  in  this  country 
during  the  years  1900-1906  might  have  escaped  the  disease, 
or  might  have  recovered  from  it,  by  observing  the  laws  of 
hygiene.  Knowing  and  heeding  what  hygiene  teaches 


12  INTRODUCTION 

would  have  enabled  100,000  of  the  200,000  victims  of 
typhoid  fever  in  the  year  1906  to  escape  the  malady. 
Living  in  a  hygienic  way  has,  in  Massachusetts,  decreased 
the  death  rate  from  tuberculosis  one  half  since  1875. 
Cities  where  the  water  and  milk  supply  are  managed 
according  to  the  demands  of  hygiene  have  less  than  one 
half  as  many  deaths  from  typhoid  fever  as  other  cities  simi- 
larly situated  but  making  no  special  effort  to  secure  pure 
milk  and  pure  water.  Four  hundred  thousand  of  the 
1,600,000  deaths  occurring  yearly  in  the  United  States 
could  be  prevented  if  the  people  understood  hygiene  and 
lived  in  accordance  with  its  teachings.  Students  of  this 
science  are  confident  that  3,000,000  of  the  8,000,000  cases 
of  serious  illness  could  be  averted  by  hygienic  living. 

Value  of  Hygiene  to  the  Young.  —  Success  in  life  depends 
largely  upon  health.  Health  depends  much  upon  habits. 
Habits  are  formed  in  youth.  The  youth  is  to  the  future 
man  what  the  roots  are  to  a  tree.  The  foundation  for 
much  of  the  illness  in  later  life  is  laid  by  the  boy  and  girl 
during  school  years.  That  instruction  which  helps  the 
pupils  to  understand  the  care  of  the  body,  and  the  true 
value  of  fresh  air,  proper  food,  exercise,  and  cleanliness, 
will  add  much  to  the  wealth  of  a  nation  and  the  happiness 
of  its  people. 

Suggestions  for  the  Teacher 

To  make  the  subjects  of  Physiology  and  Hygiene  of  real  value,  the 
teacher  must  impress  the  more  important  truths  upon  the  pupils  by 
calling  attention  to  specific  facts  related  to  the  pupils'  own  welfare. 
A  few  demonstrations  and  simple  experiments  are  of  great  use  in 
helping  the  learners  to  get  correct  and  well-fixed  ideas.  Material  for 
showing  important  structures,  such  as  the  heart,  larynx,  and  brain  of 
a  calf  or  a  sheep,  may  be  preserved  for  years  in  a  stone  jar  or  large- 


SUGGESTIONS  FOB  THE  TEACHEE         13 

mouthed  fruit  jar  containing  a  five  per  cent  solution  of  formalin. 
This  is  made  by  pouring  about  one  third  of  a  teacupful  of  formalde- 
hyde, to  be  had  at  any  drug  store,  into  a  pint  of  water. 

The  writing  of  short  essays  on  certain  topics  of  vital  importance 
not  only  will  widen  the  interest  and  knowledge  of  the  pupils,  but  also 
will  serve  to  give  valuable  training  in  expression.  A  few  bulletins 
and  reference  books  may  be  made  to  furnish  the  information  for  such 
exercises.  Many  of  the  states  publish  sanitary  bulletins  or  health 
circulars  which  may  be  had  free  of  charge  by  addressing  the  State 
Board  of  Health  at  the  capital  of  the  state.  The  following  valuable 
bulletins  will  be  sent  free  to  those  requesting  them  from  the  Depart- 
ment of  Agriculture,  Washington,  D.C.  :  Sanitary  Milk  Production ; 
Rabies  or  Hydrophobia ;  Sewage  Disposal  on  the  Farm ;  Source  and 
Nature  of  Bacteria  in  Milk  ;  Trichinosis,  a  Danger  in  the  Use  of  Raw 
Pork ;  How  Insects  affect  Health  in  Rural  Districts ;  Bovine  Tuber- 
culosis and  Public  Health  ;  Butter  Making  on  the  Farm ;  The  Unsus- 
pected but  Dangerously  Tuberculous  Cow;  Fish  as  Food;  Eggs  and 
their  Uses  as  Food;  The  Nutritive  Value  of  Foods;  The  Care  of 
Milk;  Milk  as  Food. 

The  following  reference  books  will  be  helpful  to  the  teacher  and 
should  be  in  every  school  library. 

Overton,  Frank,  Applied  Physiology.  American  Book  Company, 
N.Y. 

Eddy,  W.  H.,  Experimental  Physiology  and  Anatomy.  American 
Book  Company,  X.Y. 

Adams,  S.  H.,  The  Great  American  Fraud.  American  Medical 
Association,  103  Dearborn  Ave.,  Chicago. 

Bashore,  H.  B.,  Outlines  of  Practical  Sanitation.  John  Wiley  and 
Sons,  N.Y. 

Crandall,  F.  M.,  How  to  Keep  Well.  Doubleday,  Page,  and  Com- 
pany, X.Y. 

Frankland,  Mrs.  P.,  Bacteria  in  Daily  Life.  Longmans,  Green,  and 
Company,  N.Y. 

Public  Health  Papers  and  Reports.  C.  O.  Probst.  Columbus, 
Ohio. 

Pyle,  W.  L.,  A  Manual  of  Personal  Hygiene.  W.  B.  Saunders 
Company,  Philadelphia. 

Shaw,  E.  R.,  School  Hygiene.     Macmillan  Company,  N.Y. 

Warwick,  F.  J.,  First  Aid  to  the  Injured.  Penn  Publishing  Com- 
pany, Philadelphia. 


II.      PLAN   OF   THE   BODY 


The   Cells.  —  Since   the  year  1840  it  has  been   known 

that  all  plants  and 
animals  are  made 
up  of  one  or  more 
tiny  lumps  of  mat- 
ter called  cells.  A 
cell,  whether  in 
a  weed,  a  worm, 
or  man,  consists 
mainly  of  a  sub- 


FIG.  1.  —  A  cell  much  enlarged.  1,  surface  view; 
2,  view  of  the  upper  part  of  1  cut  through  the 
line  ae ;  p,  protoplasm ;  the  dark  spot  is  the 
nucleus  and  the  line  around  the  outside  is  the  stance  named  pro- 

cellwalL  toplasm,    which    is 

A    minute    and   usually 


egg- 


like  the  white  of  a  raw 
spherical  body  floating 
in  the  protoplasm  is  the 
nucleus.  The  thin  sac 
ordinarily  surrounding 
the  protoplasm  is  called 
the  cell  wall.  The  thin 
membrane  between  the 
successive  layers  of  an 
onion  is  formed  by  a 
single  layer  of  cells 
placed  edge  to  edge. 

Each    egg    of   a    toad    Or     FlG- 2-  —  ftliPPer  animalcules  in  a  drop  of 

water.    Photographed  through  the  micro- 

frog  when  first  deposited       scope. 

14 


THE  NATURE   OF   A   CELL, 


15 


is  a  single  cell,  but  it  is  more  than  thirty  times  as  large  as 
the  average  cell  in  the  human  body. 

The  Nature  of  a  Cell.  —  The  cell  is  called  the  unit  of 
life  because  it  is  the  smallest  portion  of  matter  capable  of 
independently  living,  eat- 
ing, and  growing.  A 
muscle  cell,  a  brain  cell, 
or  a  skin  cell  will  of 
course  not  continue  to 
live  long  when  removed 
from  the  body,  because 
it  has  no  means  of  get- 
ting food.  There  are, 
however,  in  most  pools  of 
stagnant  water  thousands 
of  free,  living  cells,  each 
of  which  is  an  animal  or 
plant .  One  of  the  largest 
and  very  easily  found 
forms  of  life  consisting  of 
a  single  cell  is  the  dipper 
animalcule,  a  million  of 
which  may  be  present  in 
a  quart  dish  of  water. 
By  adding  to  a  glass  of 
pond  water  a  small  bunch 

of  hay  or  dead  grass,  and  allowing  it  to  stand  in  a  warm 
room  a  week  or  ten  days,  numerous  slipper  animalcules 
may  be  grown.  If  a  drop  of  water  containing  them  is 
placed  on  a  glass  slip,  they  appear  to  the  naked  eye 
like  tiny  white  specks  floating  about. 


FIG.  3.  —  A  compound  microscope  such 
as  is  used  to  study  the  cells  of  the 
body  and  disease  germs. 


It) 


PLAN    OF   THE   BODY 


A  One-celled  Animal.  —  By  means  of  the  microscope  the 
slipper  animalcule  may  be  seen  to  have  the  general  shape 


FIG.  4.  —  Drawings  of  sections  of  cells.  Magnified.  6,  bone  cell;  c, 
epithelium  cell  from  the  intestine ;  e,  flat  epithelium  cell  from  the 
mouth ;  /,  fat  cell ;  n,  nerve  cell  from  the  brain ;  m,  muscle  cell. 

of  a  slipper,  though   its  outline  changes  much  when  it 
rubs  against  an  object.     The  delicate  cell  wall  is  elastic 

and  transparent,  and  is 
covered  with  fine  hair- 
like  processes  called 
cilia,  by  moving  which 
it  swims  rapidly.  A 
faintly  darker  oval  spot 
near  the  center  is  the 
nucleus.  It  takes  in 
food  consisting  chiefly 
of  tiny  plants  called 
bacteria,  through  a 
groove  011  one  side.  The 

FIG.  5.  —  Slipper  animalcule  beginning  to    B 
divide  and  thus  to  form  two  cells,  each  of    food,    when    within    the 

r»SrCaS'^rtlS  Protoplasm,  is  dissolved, 

graphed  through  the  microscope.  and  SOllie   of   it   becomes 


KINDS    OF   CELLS 


17 


a  part  of  the  animal  itself,  while  the  rest  is  pushed  out 
through  the  cell  wall.  This  tiny  living  thing  has  no 
bones,  muscles,  liver,  stomach,  blood  vessels,  lungs,  or 
nerves,  yet  it  moves,  eats,  and  gives  off  the  same  kind  of 
substances  as  those  cast  out  by  the  lungs  and  kidneys 
of  man.  It  is 
affected  by  heat, 
cold,  light,  and 
touch.  This  sin- 
gle cell  performs  a 
dozen  duties,  for 
each  of  which  in 
the  human  body 
there  is  a  separate 
group  of  cells. 

Kinds  of  Cells. — 
In  the  human 
body  there  are 
more  than  a  score 
of  different  kinds 
of  cells.  Each 
kind  has  a  special 
duty  to  perform 
and  is  worthless 
for  any  other  serv- 
ice. The  muscle  cells  are  threadlike  and  can  become 
shorter  or  longer  to  move  the  bones.  The  fat  cells  are 
nearly  spherical,  while  the  cells  lining  the  stomach  and  in- 
testines are  columnar  and  take  from  the  blood  something 
which  they  change  into  a  juice  to  dissolve  the  food.  The 
nerve  cells  are  of  various  shapes,  but  most  of  them  have 

DAV.  PHYS. 2 


FIG.  6.  —  Frog's  eggs  photographed  through  the  mi- 
croscope. A  few  hours  earlier  each  egg  was 
a  single  cell.  Some  are  now  seen  to  be  made  of 
four  cells,  some  of  eight  cells,  and  others  of  a 
greater  number  of  cells. 


18 


PLAN   OF   THE   BODY 


several  branching  processes,  one  of  which  may  be  two  or 
three   feet   long.     While  among  the  lowest  animals  one 

cell  serves  many  pur- 
poses, in  all  the  higher 
creatures  there  is  a 
different  group  of  cells 
for  each  of  the  processes 
of  life,  such  as  eating, 
moving,  and  feeling. 
This  separation  of  the 
cells  into  companies, 
each  with  its  own 
special  work,  is  known 
as  the  physiological  di- 

FIG.  7.  —  A  bit  of  muscle  as  thick  as  a  hair,    vjsjon  Of  labor. 

Growth     of     Cells.  - 

The  slipper  animalcule 
never  gets  any  larger 
than  the  point  of  a  pin.  As  soon  as  rich  food  tends  to 
make  it  grow,  the  nucleus  divides  into  two  parts,  and  a 
few  minutes  later  a  constriction,  or  furrow,  appears  cross- 
wise of  the  body.  The  furrow  continues  to  deepen,  so 
that  in  less  than  a  half 
hour  the  tiny  creature 
has  separated  into  two 
animals.  This  marvelous 
process  may  be  easily  seen 
by  placing  on  a  glass 
slide,  under  the  low  power 

of  the  microscope,  a  drop    FIG.  8. -Epithelial cells  forming  the  tissue 

lining  the  mouth  and  esophagus,     n, 

of  water   containing   the      nucleus.   Magnified. 


photographed  through  the  microscope.  In 
one  place  the  several  fibers  are  separated 
to  show  the  fibrous  connective  tissue  bind- 
ing the  muscle  fibers  together. 


ORGANS 


19 


small  beings.  These  two  new  animals  in  a  few  hours  grow 
to  full  size,  and  then  each  divides  to  form  two  others. 
Thus  in  a  few  days  from  one  tiny  animal  may  come  a  thou- 
sand. In  the  same  way  the  cells  of  the  body  are  increased, 
but  instead  of  each  leading  a  separate  existence  they  all 
cling  together  in  one  mass.  When  the  upper  cells  of  the 
skin  are  rubbed  off,  the 
ones  in  the  lower  layer 
divide,  and  so  produce 
a  new  lot  from  week  to 
week. 

The  Tissues.  —  A  com- 
bination of  cells  of  a 
similar  kind  forms  a 
tissue.  The  muscle  cells 
constitute  the  muscular 
tissue  known  as  lean 
meat  (Fig.  7).  The 

nerve  cells  make  up  the 

chief  part  of  the  nerve 
tissue  composing  the  brain,  spinal  co^d,  and  nerves.  The 
epithelial  cells,  covering  the  entire  body  and  lining  the 
alimentary  canal  and  other  tubes,  constitute  the  epithelial 
tissue  (Fig.  8).  Numerous  cells  and  fibers  serving  to  bind 
together  the  parts  of  all  the  other  tissues  are  known  as 
connective  tissue  (Fig.  9).  It  is  this  that  holds  the  skin  to 
the  muscles  and  unites  the  muscles  to  the  bones.  It  ap- 
pears as  fine  weblike  threads  in  a  piece  of  boiled  beef 
picked  to  pieces  on  the  dinner  plate. 

Organs.  —  A  group  of  tissues  having  a  special  use  is 
called  an  organ.     The  heart  is   an    organ   for   pumping 


9-Connective    tissue    fibers   photo. 
graphed  through  the  microscope. 


PLAN    OF   THE   BODY 


blood,  the  stomach  an  organ  to 
digest  food,  and  the  brain  an 
organ  concerned  in  thought. 

Systems.  — -  Several  organs, 
each  of  which  performs  a  part 
of  the  same  general  process,  con- 
stitute a  system.  The  digestive 
system  is  composed  of  the  organs 
used  in  digestion.  The  heart 
and  blood  vessels  make  up  the 
circulatory  system.  The  lungs 
and  the  air  passages  of  the  nose, 
throat,  and  windpipe  constitute 
the  breathing  or  respiratory 
system.  The  kidneys  belong  to 
the  excretory  system.  All  the 
bones  form  the  bony  or  osseous 
system,  and  the  muscles  form  the 
muscular  system.  The  brain, 
spinal  cord,  and  nerves  through- 
Era.  10.— Diagram  showing  the  out  every  part 'of  the  body  consti- 


side.  a, aorta;  op, vermiform        Each  system   is  dependent  on 
PffiiTT  "::    the  others  for  its  health.     When 

giving;   &,  kidney;   I,  canal     the    Cells    of    any    tissue    do    not 

rrS;  ':;:m    work  properly,  the  body  becomes 

np,  spines    of    vertebras;    o,     sick.       To    keep    the    body    well, 
esophagus;  s, spleen;   t,  vena  ,  ,       ,.  -, 

cava,or  great  vein ;  ^trachea      6ach     System,     each     tlSSUe,     and 

each  cell  must   do  its  own  part 

of  the  work  in  preparing,  digesting,  and  using  food,  and 
also  in  giving  off  waste  products  of  the  body.     Fresh  air, 


SUGGESTIONS   FOR   THE   TEACHER  21 

daily  exercise,  good  food,  and  temperate   habits  are   the 
surest  means  of  keeping  the  systems  in  working  order. 

Questions 

1.  Where  are  cells  found?  2.  Name  the  three  parts  of  a  cell. 
3.  What  is  a  cell?  4.  Where  can  you  get  animals  composed  of  only 
one  cell  ?  5.  Why  cannot  a  cell  removed  from  man's  body  continue 
to  live?  6.  How  does  the  slipper  animalcule  live?  7.  Name  several 
kinds  of  cells.  8.  Describe  how  the  cells  dift'er  in  shape.  9.  Describe 
the  growth  of  cells.  10.  Define  a  tissue.  11.  Name  some  tissues. 
12.  What  is  an  organ?  13.  How  many  systems  in  the  body? 
14.  What  is  the  best  way  to  keep  well  ? 

Suggestions  for  the  Teacher 

1.  Frog's  eggs,  appearing  like  dozens  of  shot  in  a  mass  of  jelly- 
like  substance  as  large  as  one's  fist,  may  be  found  during  April  in 
ponds,  and  used  to  show  how  cells  multiply.     If  the  lower  half  of 
the  eggs  are  white,  each  is  probably  a  single  cell,  and  if  they  are  kept 
in  water,  furrows  will  appear  on  the  surface  as  the  cells  increase  in 
number.     The  eggs  may  be  preserved  in  a  jar  containing  a  half  pint 
of  water  to  which  has  been  added  a  half  of  a  teacupful  of  for- 
maldehyde. 

2.  Secure  a  piece  of  transparent  membrane  just  inside  of  the  outer 
layer  of  an  onion,  and  lay  it  in  a  drop  of  water  on  a  piece  of  glass. 
By  looking  through  it  toward  the  light  with  a  common  magnifying 
glass,  thousands  of  rectangular  cells  may  be  seen. 

3.  Slipper  animalcules  may  be  produced  in  abundance  by  placing 
in  a  glass  of  stagnant  water  some  dry  grass  and  any  plant  found  grow- 
ing in  water.     The  glass  should  be  kept  for  a  week  or  more  in  a  warm 
room.     The  animals  appear  as  minute  oval  bodies  in  a  drop  of  water 
placed  on  a  glass  slide   and  examined  with  a  common  magnifying 
glass.    They  are  just  visible  to  the  naked  eye. 


III.     COMPOSITION   OF   THE   BODY 

Water.  —  The  body  of  a  person  weighing  one  hundred 
pounds  contains  in  it  about  sixty-five  pounds  of  water. 
If  an  ounce  of  beef  is  placed  in  a  warm  but  riot  hot  oven 
for  a  day,  it  will  lose  three  fourths  of  its  weight.  This 
shows  that  the  muscles  of  our  body,  which  have  about  the 
same  composition  as  lean  beef,  consist  of  only  a  fourth 
part  solid  material.  Nearly  nine  tenths  of  the  blood 
and  one  half  of  the  bones  are  made  of  water. 

Use  of  Water  in  the  Body.  —  Without  water  the  blood 
could  not  circulate  through  the  tissues  to  carry  food 
to  them  and  bring  away  the  waste  products.  Dry 
sugar  will  not  go  through  a  paper  or  membrane,  but 
when  dissolved  in  water  it  passes  through  readily.  In 
the  mouth,  stomach,  and  intestines  the  water  aids  in 
softening  and  dissolving  the  food  so  it  may  pass  into  the 
blood.  Muscles  cannot  contract  without  water,  as  they 
would  be  hard  and  fixed  like  a  piece  of  dried  beef.  The 
passing  off  of  water  through  the  skin  helps  to  keep  the 
body  cool.  In  fact,  no  organ  could  do  its  work  without 
water,  the  amount  of  which  taken  in  daily  with  food  and 
as  drink  is  about  two  quarts. 

Solids.  —  One  third  of  the  body  is  composed  of  solid 
materials  consisting  chiefly  of  the  following  substances : 

1.  mineral   matter,   such   as   salt,   soda,    lime,    and   iron ; 

2.  proteids,  like  the  white  of  an  egg  ;   3.  fats,  such  as  lard 

22 


PROTEIDS  23 

and  tallow;  4.  carbohydrates,  of  which  sugar  and  starch 
are  good  examples.  The  mineral  matter  makes  up  much 
of  the  bones,  but  in  most  other  parts  of  the  human 
structure  proteids  are  present  in  the  greatest  abun- 
dance. 

Mineral  Matter.  — This  is  the  ashes  left  after  burning 
a  piece  of  wood  or  flesh.  The  mineral  substances  form 
about  one  half  of  a 
bone  and  are  chiefly 
compounds  of  lime. 
More  than  a  teacup- 
ful  of  common  salt  is 
distributed  through- 
out the  body.  Iron  a  b 

in  amount  sufficient    FIG.  ll.  — Mineral  matter  in  muscle,    a,  piece  of 
to   make    a   piece    as       f resn  muscle  J    &>  the  mineral  matter  remaining 
after  the  muscle  was  burned. 

large  as  a  cent  oc- 
curs in  the  liver,  blood,  and  hair.  A  few  other  mineral 
compounds  are  present  in  various  organs,  but  no  gold, 
silver,  lead,  or  copper  are  constituents  of  the  human 
structure.  As  minerals  are  constantly  passing  out  of  the 
body  in  the  excretions,  a  new  supply  must  be  furnished 
by  the  food.  Milk,  meat,  eggs,  and  vegetables  contain 
all  the  mineral  substances  required  by  the  body. 

Proteids.  —  These  make  up  four  fifths  of  the  solid  part 
of  the  muscles  and  are  present  in  all  the  tissues.  The 
easiest  form  of  proteid  to  observe  is  albumin  which  with 
water  forms  nearly  all  the  white  portion  of  a  hen's  egg, 
and  is  also  the  chief  part  of  the  protoplasm  in  the  cells  of 
the  body.  Albumin  is  so  named  because  when  heated  to 
near  the  boiling  point  it  becomes  white,  and  it  is  then 


COMPOSITION   OF    THE   BODY 


changed  from  a  fluid  to  a  solid  state.     The  change  of  a 
proteid  from  a  liquid  to  a  solid  is  called  coagulation. 

The  clotting  of  blood  is  the  coagulation  of  the  proteid 
in  the  blood.  The  clabber  of  sour  milk  is  the  coagulated 
casein  which  is  the  proteid  of  milk.  Gluten,  the  proteid 
of  wheat,  may  be  separated  from  the  other  parts  of  the 
flour  by  placing  flour  in  a  handkerchief  or  muslin  bag, 
and  kneading  or  squeezing  it  ten  minutes  in  a  pan  of 

water.  The  sticky 
and  stringy  ma- 
terial left  in  the 
bag  is  the  proteid. 
Fats.  —  Fats  are 
found  in  nearly  all 
parts  of  the  body. 
They  constitute 
nearly  one  tenth  of 
the  brain,  one  fifth  of  the  nerves,  while  more  than  four 
fifths  of  the  tissue  called  adipose,  or  fatty,  is  made  of 
pure  fats.  The  fat  of  the  cow  is  known  as  tallow,  and  that 
of  the  hog  lard.  In  the  living  body  the  heat  keeps  the 
fats'  in  a  liquid  form.  Fats  which  remain  liquid  at  the 
temperature  of  a  living  room  are  called  oils.  Linseed 
oil,  olive  oil,  and  castor  oil  are  examples  of  fats  derived 
from  plants. 

To  determine  the  presence  of  fat  in  a  substance,  place  it 
on  unglazed  paper  and  warm  it  a  few  minutes.  If  fat  is 
present,  it  will  melt  and  soil  the  paper.  The  fat  of  the 
body  is  stored  in  cells  so  small  that  a  bunch  of  fifty  would 
be  no  larger  than  the  head  of  a  pin.  Most  of  our  fat  is 
made  from  the  sugars  and  starch  eaten. 


FIG.  12.  —  Fat  cells  in  the  connective  tissue  just 
under  the  skin.  6,  blood  vessel;  /,  oil;  n,  nu- 
cleus. Magnified. 


USE  OF   FAT 


25 


Properties  of  Fats.  —  Fats  will  not  form  a  lasting  mix- 
ture with  water ;  but  if  the  two  liquids  be  shaken  in  the 
same  bottle,  the  fat  will  in  a  few  minutes  rise  to  the  top. 
If  a  few  drops  of  ammonia  or  a  piece  of  potash  is  added  to 
the  liquids  before  shaking,  the  fat  is  then  broken  up  into 
tiny  globules  and  will  remain  scattered  throughout  the 
mixture.  This  is  called  an  emulsion. 

The  fats  eaten  form 
an  emulsion  in  the  in- 
testines before  they 
pass  into  the  blood. 
Milk  is  a  natural  emul- 
sion, and  therefore  an 
easy  food  to  digest.  A 
drop  of  milk  under  the 
high  power  of  the  mi- 
croscope will  show  over 
a  thousand  globules  of 
fat.  When  milk  stands 
a  few  hours,  many  of  the 
globules  rise  to  the  top 
and  form  a  layer  of  cream. 

When  any  fat  is  heated  with  a  solution  of  potash  or 
soda  and  water,  soap  is  formed.  This  process  is  called 
saponification.  Glycerine  is  made  at  the  same  time. 

Use  of  Fat.  —  The  layer  of  fat  just  beneath  the  skin  is 
from  one  tenth  to  five  tenths  of  an  inch  thick  and  pro- 
tects the  body  from  the  cold.  The  living  processes  going 
on  in  the  body  cause  the  fat  to  be  Changed  into  carbon 
dioxide  and  water.  This  change  produces  heat  to  warm 
the  body  just  as  burning  a  tallow  candle  makes  heat. 


FIG.  13.— Part  of  a  drop  oi  cream  photo- 
graphed through  the  microscope  to  show 
the  fat  globules. 


26 


COMPOSITION   OF   THE   BODY 


Fat  stored  in  the  body  can  be  used  as  food  by  the 
muscles,  heart,  and  brain  when  one  is  not  able  to  procure 
or  eat  food.  A  man  named  Tanner  lived  forty  days  with- 
out taking  any  food,  and  during  this  time  he  lost  thirty- 
six  pounds.  Almost  all  of  this  was  fat,  but  there  was 

some  loss  from  the 
other  tissues.  The  fat 
surrounding  some  of  the 
organs,  such  as  the  eye 
and  kidney,  is  useful  in 
protecting  them  from 
injury. 

Carbohydrates. — 
These  are  the  starches 
and  sugars.  More  than 
two  thirds  of  the  solid 
part  of  vegetable  foods, 
such  as  corn,  wheat, 
-,  peas,  and  potatoes,  con- 

FIG.   14.  —  A  tiny  slice  of    potato  showing  * 
three  of  the  cells  full  of  starch  grains,  sists   of   Starch.      It    OC- 

Magnified'  curs  in  the  form  of  little 

grains  which  may  be  seen  by  placing  the  scrapings  of 
a  potato  under  the  microscope.  Potato  starch  grains  are 
somewhat  egg-shaped,  out  corn-starch  grains  are  more 
cubical.  If  starch  is  chewed  in  the  mouth  for  several 
minutes,  the  saliva  will  change  it  into  sugar.  A  great 
deal  of  starch  is  present  in  green  fruit,  such  as  apples, 
pears,  and  cherries,  but  when  they  become  ripe,  the 
starch  is  changed  to  sugar. 

Use  of  Carbohydrates.  —  Starch  and  sugar,  by  means  of 
the  living  cells,   are   changed   into   carbon   dioxide   and 


SUGGESTIONS   FOR   THE   TEACHER  27 

water,  and  thereby  give  off  heat.  This  helps  to  keep  the 
body  warm.  At  the  same  time,  power  to  move  the  mus- 
cles is  also  furnished.  The  starch  and  sugar  not  used  for 
these  two  purposes  are  changed  into  fat  and  stored  up  in 
the  body. 

Questions 

1 .  How  much  of  the  body  is  composed  of  water  ?  2.  How  can  you 
separate  the  water  from  a  piece  of  beef  ?  3.  In  what  way  is  water 
useful  to  the  body?  4.  Mention  several  kinds  of  solids  present  in  the 
body.  5.  Name  some  minerals  in  the  body.  6.  Where  have  you 
seen  a  proteid?  7.  Describe  coagulation.  8.  Name  three  kinds  of 
proteids  and  tell  where  each  is  found.  9.  State  some  facts  about  fats. 
10.  How  do  you  learn  whether  fat  is  present  in  a  substance  ?  11.  How 
is  soap  formed  ?  12.  Of  what  use  is  fat  ?  13.  In  what  foods  are  car- 
bohydrates found?  14.  Of  what  use  are  carbohydrates?  15.  Why 
should  more  carbohydrates  and  fats  be  eaten  in  winter  than  in  sum- 
mer? 16.  Should  a  banker  eat  the  same  kind  of  food  as  a  black- 
smith? Why?  ' 

Suggestions  for  the  Teacher 

1.  Light  a  match  and  let  it  burn  up  completely  to  show  the  min- 
eral matter  remaining. 

2.  To  show  coagulation  let  some  milk  stand  in  a  glass  in  a  warm 
room  one  or  two  days,  or  pour  a  teaspoonful  of  vinegar  into  the  milk. 

3.  Place  a  little  of  the  white  of  egg  in  boiling  water  and  note 
the  coagulation. 

4.  Exhibit  some  lard,  tallow,  and  castor  oil  and  warm  the  first 
two  in  a  cup,  to  show  that  the  fat  of  the  body  is  in  a  fluid  condi- 
tion. 

5.  Put  a  tablespoonful  of  water  in  a  bottle  or  test  tube  and  add  a 
few  drops  of  castor  oil.     Then  shake  and  observe  how  soon  the  water 
and  oil  separate.     Now  add  twice  as  much  ammonia  as  you  did  oil 
and  shake  again.    Note  that  a  permanent  emulsion  results. 


IV.    LIFE   PROCESSES 

How  Dead  and  Living  Bodies  Differ.  —  Every  object  in 
the  universe  is  either  dead  or  alive.  Movement  is  not  a 
sure  sign  of  life.  A  trolley  car  and  a  locomotive  move,  as 
do  also  the  earth  and  the  other  planets,  yet  they  are  dead 
bodies.  Some  living  bodies,  such  as  a  blade  of  grass,  a 
flower,  or  a  tree,  have  no  motion  in  themselves,  but  they 
may  be  swayed  by  the  wind.  Living  bodies  are  able  to 
grow  and  change  their  form  and  size  by  taking  within 
them  lifeless  material  of  certain  kinds,  and  by  transform 
ing  it  into  a  part  of  themselves.  No  dead  body  can  ab- 
sorb material  from  the  soil,  as  does  a  tree,  and  change 
it  into  the  substance  of  its  own  body.  A  nestling  bird 
makes  bones,  flesh,  and  feathers  of  the  thousands  of  insects 
brought  by  the  mother. 

The  Change  from  Dust  to  Man. — Animals  and  plants 
grow  only  when  they  obtain  food  such  as  can  be  built 
into  their  bodies.  Plants  feed  on  substances  in  the  earth, 
such  as  potash,  saltpeter,  limestone,  and  gypsum,  but 
much  of  their  food  is  the  carbon  dioxide  of  the  air. 
Animals  cannot  use  any  of  these  simple  substances,  but 
must  consume  vegetables  or  animal  flesh  to  nourish  them. 
Grass  is  only  a  portion  of  the  air  and  earth  made  over  into 
a  new  form  by  sunlight  and  the  action  of  the  tiny  sprout 
from  the  grass  seed.  Some  of  this  grass  carried  into  the 
cells  of  the  cow's  body  becomes  beef,  which,  eaten  by  man, 

28 


ELEMENTS   OF   LIFE  29 

becomes  a  part  of  a  human  being.     Thus  indirectly  man's 
flesh  is  made  of  the  air  and  the  dust  of  the  ground. 

When  death  claims  the  grass,  cow,  and  man,  their  bodies 
crumble  again  to  dust  and  make  up  part  -^ 

^?!\  E vl\ 

of  the  earth.     The  crumbling,  or  decay,  xj  xl^Q 

is   produced  by  molds    and   millions   of  r — 

other  tiny  plants  called  bacteria.     In  this  r-~ 

wav  the  dead  hay  or  straw,  acted  on  by  FlG    15  _  Bacteria 

these  agents,  may  appear  the  next  sea-  which  change  dead 

.,        j  n   i  i       e  -  matter  into  a  food 

son   in   the    form    of   a  field  of  waving      for  p]ants.    Mag- 
grain.     This,  when  ground  into  flour  by      nified. 
the  mills,  becomes,  upon  being  eaten  by  man,  a  part  of 
the  human  race. 

Kinds  of  Compounds.  —  The   three   common   classes   of 

compounds  are  acids, 
alkalies,  and  salts. 
Acids  are  sour  and  turn 
blue  litmus  paper  red. 
Alkalies  are  not  sour 
and  will  turn  red  litmus 
paper  blue.  Sulphuric 
acid,  vinegar,  and  sour 
milk  are  examples  of 
acids.  Potash,  soda, 
and  ammonia  are  alka- 

FIG.    16. -Separating  wood  into  gas  and  Heg>        Table    ^     and 
charcoal,    p,  clay  pipe  containing  bits  of 

shavings  and  covered  with  mud ;   a,  alco-  limestone  are  Salts, 
hoi  lamp ;  I,  flame  made  by  the  gas  lit  as        ElementS    of    Life.  — 
it  issued  from  the  stem. 

The      elements      most 

abundant  in  a  living  body  are  carbon,  hydrogen,  oxygen, 
and  nitrogen.      Carbon  composes  half  of  the  solid  part  of 


30 


LIFE   PROCESSES 


lean  meat,  more  than  half  of  a  stick  of  dry  wood,  and  is 
plentiful  in  nearly  all  foods  eaten.  Carbon  is  the  chief 
solid  element  in  muscles,  fat,  sugars,  starches,  and  wood. 
The  other  abundant  elements  are 
gases.  If,  therefore,  some  bits  of 
wood  be  heated  very  hot  in  a  clay 
pipe  while  the  top  of  the  bowl  is 
covered  with  wet  clay  to  keep  out  the 
air,  the  gases  will  go  out  through  the 
stem,  and  as  they  issue  may  be  lighted 
with  a  match.  After  fifteen  minutes' 
heating,  carbon,  called  charcoal,  is  left 
in  the  pipe.  In  a  similar  way  gas  for 
lighting  houses  was  formerly  made  by 
heating  soft  coal  in  iron  boxes. 

Hydrogen .  —  This  is  present  in  nearly 
all  foods  and  composes  two  thirds  of 
water.  It  is  a  colorless  gas,  and  may 
be  easily  made  by  pouring  some  weak 
sulphuric  acid  into  a  bottle  containing 
a  few  nails  or  tacks.  The  iron  pushes 
off  the  hydrogen,  which  forms  part 
of  the  acid,  and  the  gas  appears  in 
bubbles  (Fig.  17).  It  will  pass  out 
of  a  glass  tube  inserted  through  the 
cork,  and  will  burn  when  a  flame  is 
applied  to  it.  This  burning  is  the 
union  of  the  hydrogen  with  the  oxygen  of  the  air.  As  a 
result  water  made  of  hydrogen  and  oxygen  is  formed. 
This  appears  in  drops  on  a  bottle  held  upside  down  at 
the  top  of  the  flame. 


FIG.  17.  —  Making  hydro- 
gen. The  bottle  con- 
tains five  nails  and 
weak  sulphuric  acid. 
To  the  right  of  the 
flame  of  hydrogen  at 
the  tip  of  the  glass  tube 
are  two  drops  of  water 
formed  by  the  union 
of  the  hydrogen  com- 
ing out  of  the  bottle 
and  the  oxygen  in  the 
air. 


PROPERTIES   OF    OXYGEN 


31 


Oxygen.  —  This  is  a  colorless  and  odorless  gas  which 
constitutes  one  fifth  of  the  air,  one  third  of  the  water,  and 
about  one  fifth  of  the  solid  portion  of  all  living  things. 
Many  lifeless  compounds  contain  it. 

Oxygen  may  easily  be  prepared  by  heating  together  in 
a  test  tube  black  oxide  of  manganese  and  chlorate  of  pot- 
asli.  To  catch  the 
gas,  arrange  a  bent 
glass  tube  with  its 
one  end  through  the 
cork  in  the  test  tube 
and  the  other  pass- 
ing just  within  the 
mouth  of  a  bottle 
filled  with  water 
and  turned  upside 
down  in  a  dish  of 
water  (Fig.  18). 
The  bottle  is  filled 
with  water  at  first 
to  expel  the  air. 

Properties  of  Oxygen.  —  Oxygen  is  the  most  important 
of  all  the  elements,  and  is  absolutely  necessary  for  the  life 
of  animals.  No  fire  can  burn  without  it.  It  differs  from 
the  other  elements  in  the  fact  that  it  may  be  made  to  join 
itself  to  nearly  all  the  elements.  Iron  exposed  to  the 
air  rusts.  The  rust  is  the  union  of  iron  and  oxygen, 
and  is  called  iron  oxide.  Carbon,  when  heated,  unites 
with  oxygen  to  form  carbon  dioxide. 

When  oxygen  combines  with  any  substance,  the  pro- 
cess is  named  oxidation.  The  substance  with  which  the 


FK;.  1H.  —  Making  oxygen,  e,  rubber  tube:  n, 
chlorate  of  potash  and  black  oxide  of  manga- 
nese ;  o,  oxygen  which  is  bubbling  out  from  t, 
the  test  tube. 


32 


LIFE  PROCESSES 


oxygen  unites  is  said  to  be  oxidized.  Burning  a  match 
means  oxidizing  the  wood.  Any  piece  of  timber  lying  out- 
of-doors  slowly  rots. 
This  is  slow  oxida- 
tion. The  oxygen 
of  the  air  is  made 
to  combine  with  the 


19.  —  A  match  being  oxidized. 


wood  by  means  of  very  tiny  plants  called  bacteria.     These 

cannot  grow  unless 

some     moisture     is 

present.     Oxidation 

produced   by  living 

cells    of    the    body 

is  constantly   going 

on   within   every 

plant    and     animal, 

and     without     this 

process    life   cannot 

continue. 

Oxidation  in  the 
Body.  —  The  oxy- 
gen of  the  air  is  re- 
ceived through  the 
nose  and  windpipe 
into  the  lungs. 
Here  it  passes  into 
the  blood,  and  is 
then  carried  to  every 
cell  in  the  body, 
where  living  action  causes  it  to  unite  with  the  tissues  or 
the  food  present.  As  a  result  heat  is  slowly  produced* 


FIG.  20.  —  Roots  of  red  clover  with  swellings 
which  are  the  home  of  bacteria  enabling  the 
plant  to  feed  on  the  nitrogen  of  the  air. 


OXIDATION   IN   THE  BODY  33 

just  as  when  the  match  was  quickly  oxidized  by  lighting 
it.  Oxidation  also  produces  energy,  which  makes  the  mus- 
cles move  the  body  and  the  other  organs  do  their  work. 
When  running  or  working  hard,  we  breathe  very  fast  in 
order  to  get  enough  oxygen  to  make  the  muscles  do  their 
work.  To  make  the  fire  burn  faster,  the  draft  must  be 
opened  below  to  send  the  air  containing  oxygen  into  the 
stove  so  it  may  oxidize  the  wood.  The  heat  thus  pro- 
duced may  be  made  to  boil  water  and  change  it  into 
steam,  which  can  be  transformed  into  power  to  run  an 
engine. 

Nitrogen.  —  This  constitutes  four  fifths  of  the  air  and 
forms  an  important  part  of  most  of  the  tissues  of  the 
body.  It  is  one  of  the  chief  elements  in  the  food  of 
plants  and  animals.  Any  substance,  such  as  skim-milk 
cheese,  containing  a  large  amount  of  it  is  called  nitrogenous 
material.  No  animals  can  make  direct  use  of  the  nitrogen 
of  the  air,  but  some  plants,  such  as  clover,  beans,  and 
peas,  are  able  to  get  it  from  the  air  and  use  it  for  food  by 
the  assistance  of  bacteria  growing  on  their  roots  and  form- 
ing little  swellings  like  the  head  of  a  pin. 

Questions 

1.  Give  two  differences  between  a  dead  body  and  a  living  body. 
2.  How  are  we  able  to  use  air  and  soil  for  food?  3.  What  changes 
dead  leaves  and  wood  to  dust  or  earth  ?  4.  Name  five  elements. 
5.  How  does  an  element  differ  from  a  compound?  6.  Name  three  kinds 
of  compounds.  7.  How  does  an  alkali  differ  from  an  acid  ?  8.  What 
four  elements  are  most  abundant  in  man?  9.  How  can  you  make 
carbon?  10.  Describe  the  preparation  of  hydrogen.  11.  Explain 
oxidation.  12.  Why  are  the  drafts  of  a  stove  opened  below  to  make 
the  fire  burn  ?  13.  Why  do  we  breathe  faster  when  at  hard  work  ? 
14.  Where  is  nitrogen  found  ?  15.  Why  must  one  eat  some  nitrogenous 
food? 

DAV.   PHYS. 3 


34  LIFE  PROCESSES 

Suggestions  for  the  Teacher 

1.  Fill  the  bowl  of  a  clay  pipe  with  wood  shavings  and  cover  over 
the  top  with  wet  clay  or  mud.     Heat  over  a  hot  flame,  and   in   five 
minutes  the  gas  issuing  from  the  stem  inclined  upward  may  be  lit. 
When  the  gas  which  is  formed  from  the  carbon  and  hydrogen  of  the 
wood  ceases  to  burn,  carbon  will  remain  in  the  bowl  of  the  pipe. 

2.  Place  in  a  small  bottle  water  to  the  depth  of  two  inches  and 
add  a  half  inch  of  sulphuric  acid.     Prepare  a  tight-fitting  cork  con- 
taining a  hole,  through  which  is  thrust  a  small  glass  tube.     Drop  into 
the  bottle  a  dozen  tacks  or  nails,  then  insert  the  cork,  and  after  five 
minutes,  try  lighting  the  colorless  gas  coming  from  the  tube.     Use  a 
long  splinter  and  stand  oft'  about  two  feet  from  the  bottle  to  avoid  any 
accident  that  might  possibly  occur.     Do  not  let  acids  drop  upon  the 
clothing  or  the  hands. 

3.  Hold  a  vial  over  the  flame  formed  in  experiment  2  and  note  the 
water  forming  on  the  glass.     Explain. 

4.  Ask  one  of  the  pupils  to  secure  the  roots  of  a  clover,  bean,  or  pea 
plant  growing  in  loose  soil.     After  it  is  washed,  let  him  show  in  class 
the  swellings  or  tubercles  produced  by  the  growth  of  bacteria  taking 
nitrogen  from  the  air. 


V.     FOOD   AND   ITS  USES 

Need  of  Food.  —  Food  is  required  to  replace  dying  parts 
and  to  furnish  heat  and  energy.  The  weight  of  a  boy 
after  taking  part  in  a  game  of  football,  or  other  vigorous- 
exercise,  during  which  no  water  or  food  has  been  taken, 
will  be  several  ounces  less  than  before  the  play  ;  but  in 
the  same  period  the  weight  of  the  boy  who  sat  quietly  and 
watched  the  game  will  show  almost  no  decrease.  This- 
shows  that  the  muscles  wear  out  by  use.  Some  of  the 
worn-out  parts  pass  off  in  the  sweat  and  breath.  The 
temperature  of  the  body  is  the  same  in  both  cold  and  warm 
weather.  This  shows  that  material  is  being  burned  inside 
of  it  to  produce  heat.  Food  must  therefore  be  supplied 
to  replace  what  is  burned  up  to  keep  the  body  warm. 

Kinds  of  Foods.  —  The  term  food  includes  everything 
that  is  consumed  for  the  purpose  of  nourishing  the  body 
or  supplying  it  with  heat  and  energy.  The  five  chief  food 
stuffs,  or  proximate  principles,  are  mineral  salts,  water,  pro- 
teids,  fats,  carbohydrates.  All  these  substances  except 
either  carbohydrates  or  fats  are  absolutely  necessary  to 
maintain  the  body  in  health.  Proteids  serve  to  replace 
dying  particles  of  tissues.  As  both  the  carbohydrates  and 
fats  are  used  largely  for  furnishing  heat  and  energy,  either 
one  may  be  dispensed  with,  provided  an  extra  supply  of 
the  other  is  used. 

Mineral  Salts  and  Water.  —  These  are  necessary  for 

35 


36  FOOD   AND   ITS   USES 

the  proper  nourishment  of  the  body.  A  little  common 
salt  is  present  in  all  meat,  but  to  make  it  palatable,  more 
is  usually  added.  The  salts  of  potash,  lime,  and  iron  are 
present  in  many  vegetables  and  fruits.  Dr.  Forster  fed 
dogs  with  food  from  which  all  the  salt  had  been  extracted, 
and  as  a  result  they  died  in  about  one  month.  An  adult 
takes  daily  with  his  food  about  as  much  table  salt  as  can 
be  held  on  a  large  tablespoon.  Lime  salts  are  especially 
necessary  in  the  young  to  help  build  the  bones.  Iron  salts 
are  constantly  needed  to  form  an  important  part  of  the 
red  blood  corpuscles. 

Water  is  a  carrier  of  the  foods  through  the  body  and 
an  aid  to  the  organs  in  performing  their  functions.  More 
than  half  of  most  foods  consists  of  water. 

Proteids.  —  The  white  of  egg  is  composed  of  water  and 
albumin,  which  is  one  of  the  commonest  forms  of  proteid. 
Lean  beef  is  made  almost  entirely  of  proteid  and  water. 
Skim-milk  cheese  consists  of  nearly  one  third  proteid  and 
two  thirds  water.  Proteids  form  a  part  of  every  cell  in 
all  plants  and  animals. 

Heating  a  proteid  or  adding  to  it  either  alcohol  or  ni- 
tric acid  usually  causes  it  to  coagulate,  that  is,  form  a 
tough,  jellylike  mass  similar  to  the  boiled  white  of  egg. 
The  proteid  part  of  food  keeps  the  tissues  of  the  body  in 
repair.  If  more  proteid  is  eaten  than  is  necessary  to  re- 
build the  worn-out  part  of  the  machine,  it  may  be  trans- 
formed into  fat  and  may  also  provide  heat  and  energy  by 
becoming  oxidized. 

Carbohydrates.  —  Sugar  and  starch  are  nearly  pure  carbo- 
hydrates. Starch,  which  occurs  abundantly  in  most  vege- 
table foods,  is  the  source  from  which  the  body  derives 


STIMULANTS  3? 

nearly  all  its  carboh}Tdrate  materials.  More  than  half  of 
wheat  bread,  dried  peas,  beans,  and  corn  consists  of 
carbohydrates,  and  more  than  three  fourths  of  wheat  flour 
and  rice  is  made  of  carbohydrates.  Meat  contains  almost  no 
carbohydrate  material,  and  eggs  none  whatever.  Carbo- 
hydrates furnish  most  of  the  energy  of  the  body  and 
some  heat.  When  eaten  in  large  quantities,  they  tend 
to  make  a  person  fat. 

Fats.  —  Fat  occurs  in  most  animal  foods.  Butter  is  the 
kind  of  fat  present  in  milk.  Cream  cheese  is  nearly  one 
third  fat,  and  eggs  about  one  eighth  fat.  The  fats  ex- 
tracted from  plants  are  often  called  oils.  Such  are  cotton- 
seed oil,  linseed  oil,  and  castor  oil.  Very  little  fat  is 
present  in  most  vegetable  foods.  Fat  eaten  and  taken  to 
the  tissues  is  made  to  unite,  with  oxygen  received  into  the 
blood  from  the  lungs,  and  by  this  union  heat  is  pro- 
duced. The  consumption  of  more  fat  than  the  body 
needs  may  cause  one  to  become  fat. 

Condiments  and  Flavors.  —  Pepper,  salt,  vanilla,  cinna- 
mon, nutmeg,  vinegar,  and  mustard  are  called  condiments, 
or  flavors.  They  are  generally  added  for  the  purpose  of 
making  food  more  appetizing.  The  pleasant  odors  and 
spicy  tastes  increase  the  flow  of  the  digestive  juices,  and 
in  that  way  aid  digestion  and  so  increase  the  real  value  of 
the  food  eaten.  Too  much  of  the  condiments,  especially 
pepper,  vinegar,  and  mustard,  may  have  an  unwholesome 
effect  on  the  cells  of  the  stomach  and  some  of  the  other 
organs. 

Stimulants.  —  Tea,  coffee,  cocoa,  chocolate,  beef  tea,  and 
alcoholic  drinks  are  called  stimulants  because  sometimes 
they  hasten  the  action  of  certain  organs.  They  are  all  dis- 


FOOD   AND   ITS   USES 

cussed  in  a  later  chapter,  with  the  exception  of  beef  tea. 
This  contains  very  little  nourishment,  but  is  of  great  value 
in  setting  the  digestive  glands  to  work,  and  thus  preparing 
for  the  true  food  which  should  follow  later.  The  use  of 
much  beef  tea  is  harmful. 

There  is  a  dispute  as  to  whether  alcohol  is  really  a  food. 
Whether  a  food  or  not,  there  is  danger  in  using  it,  owing 
to  the  fact  that  many  thousands  yearly  acquire  an  alcohol 
thirst  which  causes  much  ill  health  and  many  untimely 
deaths.  The  Harveian  Society  has  shown  that  one  seventh 
of  the  deaths  of  adults  in  London  are  due  to  alcoholic 
drink.  Numerous  experiments  and  observations  made  by 
business  men  and  scientists  prove  that  alcoholic  drinks, 
such  as  beer,  whisky,  and  wine,  form  the  greatest  single 
factor  in  the  making  of  criminals  and  paupers  in  this 
country. 

Food  Values.  —  The  real  value  of  food  does  not  depend 
upon  the  amount  eaten  but  upon  how  much  is  digested 
and  carried  from  the  alimentary  canal  into  the  tissues  of 
the  body.  Food  has  two  kinds  of  value :  a  tissue  value 

and  a  fuel  value.  Proteids, 
such  as  lean  meat  and  skim 
milk,  have  largely  a  tissue 
value  because  they  can  be 
Q  &  used  in  building  up  the 

FIG.  21. -Heat-making  power  of  food.  t      Q£    th  u      and    ^ 

a,  amount  of  fat  required  to  make  * 

one  calorie  or  heat  unit;  6,  quantity  SU6S        being       Worn        out. 

of  sugar  or  pure  proteid  necessary  cllo,arq     t.^  flrifq     -fa-pl^, 

to  produce  one  calorie.  Hlgars,    1   -tS,  an 

have    a    large    fuel     value 

because     they    unite    with    oxygen    in    the    body    and 
produce   heat,   muscular  movement,  and  activity  of  the 


AMOUNT   OF   FOOD    NEEDED 


39 


organs.  The  fuel  value  is  reckoned  in  heat  units.  Ex- 
periments show  that  food  burned  outside  of  the  body  gives 
off  the  same  quantity  of  heat  as  when  oxidized,  or  burned 
by  the  living  cells  in  the  body. 

Amount  of  Food  Needed.  —  Most  people  eat  too  much 
of  one  kind  of  food,  such  as  meat  or  sweets.  No  one  can 
live  on  sugar  and  fat  alone  longer  than  a  few  weeks,  because 


meal 


Fio.  22.  —  Diagram  showing  the  difference  in  cost  of  three  foods  each  of 
which  furnishes  about  the  same  amount  of  nourishment. 


these  substances  have  no  tissue  value  and  cannot  rebuild 
the  worn-out  cells.  They  have  only  a  fuel  value,  giving 
heat  and  energy.  A  man  at  hard  labor  needs  much  more 
fats  and  starches  as  fuel  to  furnish  energy  than  one  who 
is  idle.  Experiments  on  hundreds  of  persons  show  that 
the  average  man  should  have  daily  /0oc?  containing  one 
eighth  of  a  pound  of  pure  proteid  for  the  tissues,  and 


40  FOOD   AND   ITS   USES 

there  should  also  be  fats  and  starches  to  furnish  a  fuel 
value  of  3000  heat  units.  A  woman  needs  about  one  fifth 
less.  To  select  food  with  the  proper  fuel  and  tissue  value, 
one  must  know  of  what  certain  meats  and  vegetables  are 
composed. 

Diet.  —  Diet  is  a  course  of  food  selected  with  reference 
to  health.  A  knowledge  of  diet  is  important  not  only 
because  it  enables  one  with  a  small  amount  of  money  to 
select  the  most  suitable  fare,  but  because  a  proper  diet 
does  much  in  preventing  sickness  and  in  helping  the  sick 
to  get  well.  Recent  studies  have  shown  that  if  the  proper 
attention  were  given  to  the  tissue  and  fuel  value  of  food, 
the  people  of  this  country  could  purchase  the  same  amount 
of  nourishment  as  they  now  take  for  $500,000,000  less 
annually  than  the  present  cost. 

In  some  institutions  of  learning  where  the  average  price 
of  board  is  three  dollars  per  week,  the  boys  anxious  to 
economize  have  been  known  to  board  themselves  in  their 
room  at  a  cost  of  only  seventy-five  cents  per  week.  The 
daily  fare  generally  consisted  of  one  quart  of  milk,  some 
fruit,  and  sufficient  bread  and  oatmeal  to  satisfy  the  appe- 
tite. These  foods  are  rich  in  proteid  and  have  a  large  fuel 
value. 

Oysters,  fish,  and  beef  sirloin  are  expensive  foods.  Skim 
milk,  potatoes,  oatmeal,  wheat  bread,  and  corn  mush  are 
cheap  foods  that  furnish  the  necessary  nourishment.  The 
table  on  the  following  page  (Fig.  23)  shows  that  ten  cents' 
worth  of  corn  meal  contains  five  times  as  much  proteid 
and  has  ten  times  as  much  fuel  value  as  ten  cents'  worth 
of  beef  sirloin. 

In  sickness  the  diet  is  more  important  than  medicine. 


DIET 


41 


1 

-0     3D     00     < 

If 

CL 

Eggs 
Wheat  bread 
Corn  meal 

H.t  rma.l 

Cheese,  cream 

5 

* 

f 

0 
I 

i 

0. 

I 

T 

L 

II 

f 

If 
If 

• 
5" 

^_ 
I 

TEN  CENTS 
WORTH  OF 

H 
CO 

r~ 

m 

*  55.^ 

— 

is 

CO 

-                    —       Q. 

- 

O  I 

p- 

C 

r 

m 

1 

1 

| 

I 

| 

9 

I 

1 

10 

O 

c 
z 

u> 

m 
0 

O 

0 

TJ 

o 

m 

H 

? 

H 

m 

0 

H 

Oi 

0 

S 

1 

1 

1 

1 

1 

1 

o 

8 

CO 

' 

o 
o 

T 

m 
—  j 

O 
O 
O 

o 

c 
z 

H 

C/) 

3 

3} 

Jh 

0 
•n 

•n 

m 

z 

Ul 

m 

r~ 

0 

m 

z 

Oi 

o 

§ 

c 
m 

H 

I 

42  FOOD   AND   ITS   USES 

The  recovery  from  dyspepsia,  typhoid  fever,  tuberculosis, 
and  all  bowel  troubles  depends  largely  upon  the  diet  of 
the  patient.  Constipation,  or  clogging  of  the  large  intes- 
tine, and  appendicitis,  sometimes  resulting  from  it,  may  be 
avoided  in  many  cases  by  choosing  a  diet  from  such  foods 
as  corn-meal  mush,  bread  from  whole  wheat,  dried  and 
fresh  fruits,  rhubarb,  onions,  tomatoes,  peas,  beets,  spinach, 
liver,  and  wild  game.  Much  water  should  also  be  taken. 
Hot  bread,  crackers,  pastry,  cake,  dried  and  smoked 
meats,  cheese,  boiled  milk,  tea,  potatoes,  and  rice  should 
seldom  be  eaten  by  one  troubled  with  constipation. 

It  is  said  that  Germany  owed  her  success  in  the  Franco- 
Prussian  War  to  diet.  The  disease  of  beriberi,  once  so 
common  in  the  Japanese  army,  was  held  in  check  by  using 
certain  foods  and  avoiding  others.  Scurvy,  so  prevalent 
among  the  sailors  and  explorers  years  ago,  now  seldom 
occurs  because  more  vegetables  and  less  dried  and  salt 
meats  are  used. 

Fruits.  —  Most  fruits  contain  a  large  percentage  of  water 
and  only  a  small  amount  of  the  food  elements.  However, 
they  form  a  very  important  part  of  the  diet  because  of 
their  agreeable  flavor,  which  increases  the  flow  of  the 
digestive  juices,  helping  in  the  digestion  of  the  other  foods. 
They  aid  much  in  stimulating  in  a  healthy  way  the  activity 
of  the  digestive  organs,  which  otherwise  may  become  slug- 
gish and  then  be  harmed  by  the  careless  use  of  pills  or 
other  drugs.  Ripe  fruits  also  furnish  some  of  the  mineral 
foods.  Overripe  fruit  and  unripe  fruit  should  never  be 
used. 

Adulteration  of  Foods.  —  A  food  is  said  to  be  adulter- 
ated when  a  cheaper  material  is  mixed  with  it  or  some 


SPECIAL   FOODS  43 

chemical  is  employed  to  preserve  it.  Alum  is  sometimes 
added  to  wheat  flour  to  increase  the  whiteness.  Wheat 
flour,  gypsum,  clay,  and  radish  seeds  are  often  present  in 
prepared  mustard.  Ground  corn,  rice,  buckwheat  hulls, 
cocoanut  shells,  crushed  olive  stones,  and  sawdust  are 
frequent  adulterants  of  pepper.  Coffee  is  occasionally 
adulterated  with  the  ground-up  root  of  the  chicory  plant. 
Olive  oil  sometimes  contains  large  quantities  of  cotton- 
seed and  peanut  oils.  Milk  is  frequently  diluted  with 
water. 

Of  8651  samples  of  food  examined  in  Massachusetts  in 
1904,  over  twenty-six  per  cent  was  found  to  be  adulterated. 
As  only  those  foods  thought  to  be  of  poor  quality  were 
selected,  it  is  probable  that  the  actual  proportion  of  adulter- 
ated foods  in  the  market  is  much  less..  The  recently 
enacted  pure  food  laws  and  the  appointment  of  inspectors 
are  doing  much  to  lessen  the  sale  of  impure  foods. 

Special  Foods.  —  The  breakfast  foods  which  are  sold 
cooked  and  ready  for  the  table  are  pure  and  wholesome, 
as  most  of  them  are  made  from  steamed  and  crushed 
wheat,  oats,  or  corn.  For  nourishment,  well-cooked  oat- 
meal is  equal  to  them,  is  much  cheaper,  and  is  quite  as 
palatable  when  mixed  with  a  few  chopped  dates,  figs,  or 
bananas. 

Renovated  butter,  made  by  purifying  a  rancid  or  poor 
quality  of  butter,  is  sold  at  a  lower  price  than  genuine 
butter,  but  contains  about  the  same  food  value.  Butterine 
and  oleomargarine,  of  which  70,000,000  pounds  are  sold 
yearly,  are  made  from  tallow,  lard,  cottonseed  oil,  and 
cream.  They  are  good  foods,  but  are  not  worth  so  much 
as  butter.  Fruits,  vegetables,  and  meats  put  up  in  cans 


44  FOOD   AND  ITS   USES 

are  usually  wholesome,  but  it  is  preferable  to  use  the  fresh 
articles  when  they  can  be  obtained. 

Cooking.  —  Foods  are  cooked  for  three  purposes:  to  ren- 
der them  more  easily  digestible,  to  develop  the  flavors,  and 
to  kill  the  germs  of  disease  which  occasionally  may  be  pres- 
ent. Meats  are  most  healthful  when  baked,  roasted,  boiled, 
or  broiled.  To  boil  meats  and  vegetables,  they  should  be 
at  the  first  immersed  in  boiling  water  to  coagulate  the  sur- 
face layer,  and  thus  prevent  the  escape  of  the  nourishment. 
In  making  stews  and  soups,  the  meat  and  vegetables 
should  be  put  into  cold  water  and  slowly  heated  to  near 
the  boiling  point.  In  this  way  the  water  draws  out  the 
flavors  and  nourishment  to  form  delicious  soup.  Old 
bread  and  toasted  bread  are  much  more  easily  digested 
than  that  newly  baked.  Fried  foods  often  cause  indi- 
gestion. 

Sard-foiled  eggs  are  not  so  easily  digested  as  those  par- 
tially cooked.  A  good  method  of  preparing  eggs  for  the 
table  is  to  put  them  in  a  pan  off  the  stove  and  pour  on 
sufficient  boiling  water  to  cover  them  one  inch  deep.  In 
fifteen  or  twenty  minutes  the  white  will  be  in  a  creamy 
state  easy  to  digest,  and  the  yolk  will  also  be  well  cooked, 
but  not  hard.  Eggs  thus  cooked  are  easily  digested  by 
invalids  and  year-old  children. 

To  cook  food  so  that  it  shall  be  highly  nutritious  and 
delicious,  is  an  art  which  every  girl  ought  to  acquire. 
Poorly  cooked  food  causes  ill  temper,  ill  health,  and  un- 
happiness.  The  dry  and  insipid  bread  often  bought  at  the 
store  or  bakery  should  not  replace  the  appetizing  home- 
made article.  The  girl  who  knows  how  to  prepare  a 
dainty  meal  and  serve  it  with  a  pleasant  smile  is  sunshine 


SUGGESTIONS  FOR  THE  TEACHER         45 

in  any  home.     The  boys  who  obtain  the  greatest  profit 
and  pleasure  from  camping  know  how  to  cook. 

Questions 

1.  What  is  a  food?  2.  Which  of  the  food  stuffs  are  necessary  to  life  ? 
3.  Where  do  proteids  occur  ?  4.  What  foods  contain  much  carbohy- 
drate? 5.  Mention  a  food  containing  no  carbohydrate.  6.  Name 
several  kinds  of  fats.  7.  What  is  the  effect  in  some  cases  of  eating 
much  fat  and  carbohydrates  ?  8.  What  evidence  can  you  give  show- 
ing that  some  mineral  salts  are  necessary  for  health  ?  9.  How  much 
water  does  a  man  take  into  his  body  daily?  10.  Which  of  the  condi- 
ments may  harm  the  system?  11.  What  are  stimulants ?  12.  Give 
three  reasons  why  alcoholic  drinks  should  not  be  used.  13.  What  two 
kinds  of  value  has  food?  14.  How  does  food  keep  the  body  warm? 
15.  How  much  food  does  an  average  man  need  daily?  16.  Explain 
why  five  cents'  worth  of  corn  meal  is  of  more  value  as  a  food  than 
twenty-five  cents'  worth  of  sirloin.  17.  Show  that  five  cents'  worth 
of  oatmeal  has  as  much  food  value  as  twenty-five  cents'  worth  of 
mutton  leg.  18.  Why  is  ten  cents'  worth  of  beans  equal  in  food  value 
to  a  dollar's  worth  of  oysters?  19.  Of  what  importance  is  diet  in 
sickness?  20.  Describe  renovated  butter,  butterine,  and  oleomar- 
garine. 

Suggestions  for  the  Teacher 

1.  Ask  a  pupil  to  weigh  a  peeled  apple,  and  after  drying  it  in  the 
oven  a  day  or  two,  to  weigh  it  again.     Request  another  pupil  to  do 
the  same  with   a  potato.     Calculate  what  part  of  these   foods  is 
water. 

2.  Ask  several  of  the  pupils  to  try  cooking  eggs  at  home  so  that 
the  yolk  may  be  made  palatable  and  yet  the  white  remain  like  a  thick 
cream  instead  of  being  rendered  hard  and  tough. 


VI.   MICROBES  AND  MOLDS 

The  Ancient  Belief  as  to  the  Origin  of  Life.  —  Until  the 
middle  of  the  last  century,  people  generally  believed  in  what 
is  known  as  spontaneous  generation.  This  is  the  changing 
of  dead  particles  of  matter  into  living  forms  without  the 
aid  of  any  other  life.  Aristotle  said  over  2000  years  ago 
that  some  animals  spring  from  putrid  matter,  certain  in- 
sects come  from  dew,  threadworms  originate  in  the  mud 
of  wells,  and  lice  proceed  from  the  flesh  of  other  creatures. 
Even  to-day  some  people  believe  that  the  maggots,  or  little 
wormlike  animals  found  on  meat  in  warm 
weather,  have  come  from  the  meat.  The 
fact  is  that  the  maggots  result  from  the 
FIG.  24.  -  Bacteria  hatching  of  the  eggs  of  flies  which  were 

that  cause   meat 

to  spoil.   Magni-   lai(l  on  the  meat. 

fied-  If  flies  are  kept   away  from   meat   in 

warm  weather  by  netting,  it  will  nevertheless  spoil.  The 
microscope  shows  that  the  spoiling  is  due  to  millions  of 
tiny  plants  now  called  bacteria. 

Discovery  of  the  Cause  of  the  spoiling  of  Food.  —  Milk 
or  meat  broth  standing  exposed  a  day  or  two  in  warm 
weather  begins  to  decay.  In  it  are  formed  great  numbers 
of  bacteria  which  until  forty  years  ago  were  thought  by 
many  to  be  particles  of  the  milk  or  broth  changed  to  life 
by  spontaneous  generation.  Tyndall,  Pasteur,  and  others 
have  shown  that  the  bacteria  came  from  the  growth  of 

46 


THE   NATURE   OF   BACTERIA  47 

other  bacteria  always  found  floating  in  the  air.  This  was 
proved  by  placing  some  broth  in  several  jars,  some  of  which, 
after  being  boiled  to  kill  all  life,  were  tightly  sealed,  while 
the  others  were  left  open.  In  a  few  days  all  of  those  re- 
maining open  were  found  to  contain  numerous  tiny  living 


FIG.  25. — Mold  growing  on  bread.  The  little  knobs  on  the  top  of  some 
of  the  threads  contain  hundreds  of  tiny  round  bodies  called  spores  or 
germs.  These  break  loose  and  being  blown  rbout  get  on  food  and  cause 
another  growth  of  mold. 

and  moving  bodies.     Even  after  weeks  the  sealed  jars  con- 
tained no  life. 

The  Nature  of  Bacteria.  —  Bacteria  are  one-celled  plants. 
They  are  often  called  microbes  or  germs.  Minute  one-celled 
animals  are  also  called  microbes  or  germs.  A  piece  of  mold 
is  sometimes  spoken  of  as  a  germ.  Molds  differ  from  bac- 
teria in  being  much  larger,  forming  long  threads,  and  not 
dividing  in  the  middle  to  produce  new  plants.  Some  molds 
are  useful  in  giving  flavor  to  cheese,  others  cause  decay  in 
any  vegetable  or  animal  material  on  which  they  grow,  and 


48 


MICROBES   AND   MOLDS 


a  few  kinds  may  produce  disease,  such  as  ringworm  and 

barber's  itch. 

Over  1000  different  kinds  of  bacteria  are  now  known, 

but  it  is  impossible,  except  in  a  few  cases,  to  distinguish 

one  kind  from 
an  other  by  merely 
'  examining  them 
with  the  micro- 
scope, because 
several  different 
varieties  have  ex- 
actly the  same 
shape.  There  are 
three  general 
forms:  the  spheri- 
cal ones,  named 
cocci;  the  rodlike, 
known  as  bacilli; 

FIG.  26.  —  This  flat  cell,  having  on  its  surface  over  and     the     curved 
200  bacteria,  is  from  the  mouth  of  a  well  person.  .,  . 

Thousands  of  such  cells  with  bacteria  are  present  oneS,    Called     spl- 

in  all  mouths.    Photographed  through  a  micro-  rilla.      The  bacilli 
scope. 

are  the  most  com- 
mon forms,  but  the  spirilla  are  the  largest,  some  of  them 
in  stagnant  water  being  easily  seen  under  a  microscope 
magnifying  only  100  diameters. 

Bacteria  are  abundant  in  milk,  water,  soil,  and  air.  A 
bit  of  rich  earth  as  large  as  a  pea  may  contain  over 
5,000,000.  The  usual  water  often  consumed  in  one  drink 
contains  more  than  50,000,  and  a  glass  of  good  buttermilk 
has  in  it  millions  of  bacteria.  Vast  numbers  live  on 
the  surface  of  the  body,  and  millions  dwell  in  the  alimen- 


BACTERIA    AND    DISEASE  49 

tary  canal,  while  still  others  are  being  blown  about  in  the 
air.  When  the  air  is  quiet,  they  settle  down  and  stick 
fast  on  all  moist  surfaces.  Most  bacteria  are  harmless  to 
man'when  taken  into  the  nose  or  stomach.  A  few  kinds 
produce  disease,  and  some  others  are  of  great  use  in 
nature. 

How  Bacteria  grow  and  Multiply.  —  With  favorable  sur- 
roundings, such  as  warmth,  moisture,  and  food,  bacteria 
increase  rapidly  in  num- 
bers. Their  method  of 

growth     is     to     lengthen   FlG-  27.— Diagram  showing  how  bacteria 

divide  to  form  new  bacteria. 

out  slightly  and  then  to 

divide  crosswise  into  two  equal  parts.  A  germ  can  divide 
every  half  hour  so  that -one  plant  might  produce  many 
millions  of  descendants. in  one  day.  Most  of  them  can 
live  for  months  in  a  dry  state,  and  some  can  remain  alive 
all  winter  in  a  cake  of  ice.  Certain  kinds  are  able,  when 
food  fails,  to  surround  a  portion  of  their  living  material 
with  a  thick,  protecting  coat,  and  thus  form  a  spore  (Fig. 
28).  The  spores  of  some  germs  may  be  boiled  over 
twenty  minutes  without  killing  them.  Fortunately  none 

of  our  common  disease-producing  bacteria  can 

form  spores,  and  they  are   therefore   easily 

killed  by  heat. 

Bacteria  and  Disease.  —  Only  about  twenty 

different  kinds  of  bacteria  produce  disease  in 

FIG.  28. -Bac-  .- 

teria,  four  of  m^n-     Diseases  caused  by  germs  are  known 
which  contain  as  infectious  diseases  because  the  germ  infects 
or  makes  its  way  into  the  body.     Bacillus 
tuberculosis  causes  consumption,  scrofula,  and  white  swell- 
ing.   The  diphtheria  bacilli,  growing  in  the  throat,  produce 

DAT.  PHYS.  4 


50 


MICROBES    AND   MOLDS 


diphtheria.  Pneumonia,  sore  throat,  and  colds  occur 
when  certain  bacteria  are  present  in  great  numbers. 
Whether  disease-producing  bacteria,  after  gaining  en- 
trance to  the  body,  shall  cause  disease  or  not,  depends  upon 

the  ability  of  the  tissues 
to  destroy  them. 

How  Bacteria  produce 
Disease.  —  Bacteria  must 
get  into  the  tissues  and 
multiply  in  order  to  cause 
disease.  They  may  find 
entrance  through  the  ali- 
mentary canal,  the  lungs, 
or  the  skin.  Germs  like 
those  of  tuberculosis  and 
typhoid  fever  may  reach 
the  intestine  with  food  or 
water,  and  penetrate  the 
cells  there,  and  even  pass 

FIG.  29. -Germs  that  cause  tuberculosis      through   the  walls  of   the 


or  consumption  growing  in  clusters  ap- 
pearing as  white  spots  on  a  piece  of 
potato  smeared  with  glycerine. 


intestine  into  the  blood 
to  be  carried  to  any  part 
of  the  body.  Throwing 
dead  animals  or  waste  matter  into  a  stream  of  water  is  a 
crime,  because  the  bacteria  in  them  may  cause  disease  and 
death  to  persons  living  along  the  stream  and  using  the 
water  for  drinking.  With  the  air,  bacteria  enter  the 
lungs  when  some  of  the  ciliated  cells  lining  the  air  tubes 
are  injured.  A  break  in  the  skin  or  even  a  faulty  skin 
gland  may  permit  bacteria  to -reach  the  tissues  beneath 
and  produce  a  running  sore;  or  blood  poison  may  result 


THE   USEFUL   BACTERIA  51 

if  they  are  carried  through  the  system.     Knives,  needles, 
and   dressings  used   in  any  operation,  such  as  removing 
a  splinter,  or  vaccination,  should  first  be 
boiled  to  kill  the  germs  on  them.  O  O  o 

Bacteria  injure  the  body  in  two  ways.  O^QQ 

They  consume  the  tissue,  and  they  give  ®@^ 

off  poisons.  The  bacteria  causing  boils  FlG  30. —  Bacteria 
eat  away  the  tissues  so  as  to  form  little  that  cause  boils. 

Magnified. 

holes,  but   they   do   not   give   off   much 
poison.      The   diphtheria   bacilli   do   not    destroy    much 
tissue,  but  excrete  a  great  deal  of  poison,  affecting  the 
heart  and  other  organs. 

The  Useful  Bacteria.  —  The  souring  of 
cream   for  churning,  the   flavor  of  some 
cheese,    the    manufacture   of    linen,    the 
FIG.  si.  -  Bacteria  making  °f   vinegar,  and   the  fertility  of 
that  cause  milk  to  the  soil  depend  upon  different  groups  of 
bacteria.     The  action  produced   by  bac- 
teria  on   any  substance  is  known  as  fermentation.     The 
cider  by  means  of  yeast  always  present  on  fruit  is  fer- 
mented  to   form   a  weak  alcohol, 
and  then  certain  bacteria  by  fer- 
mentation  change   the  alcohol   to 
vinegar. 

Straw,  hay,  and   the   bodies   of  FlG.  32.  -  Plants 'that  cause 
dead  animals  cannot  decay  without      fermentation,  a,  yeast 

r  •  mi  •      •?  i       i    i    i  plants  which  change  cider 

bacteria.  This  decay  is  absolutely  £*^  to  alcohol ;  6,  bac- 
necessary  before  dead  material  can  teria  which  change  the 
become  food  for  the  green  plants. 

If  there  were  no  bacteria  to  rot  waste  matter  and  thus 
fertilize  the  soil,  the  plants  would  soon  use  up  all  the 


52  MICROBES    AND   MOLDS 

nourishment  in  the  ground  and  die.  The  animals  would 
then  have  no  food,  and  their  death  must  result,  and  man 
would  follow  the  same  fate.  It  is  evident,  therefore,  that 
this  world  is  saved  from  becoming  a  dreary  waste  by  the 
action  of  tiny  bacteria. 

The  Preserving  of  Food.  —  Since  intense  cold  prevents 
the  growth  of  bacteria  and  molds,  foods  are  put  in  ice 
houses  and  refrigerators  to  prevent  spoiling.  Meat  at 
freezing  temperature  may  be  preserved  for  years.  Some 
meats,  such  as  smoked  ham  and  dried  beef,  have  been 
soaked  in  a  salt  solution  several  weeks  or  well  rubbed 
with  salt,  and  then  smoked  and  dried  on  the  surface. 
This  keeps  out  the  bacteria,  and  the  salt  restrains  greatly 
the  growth  of  bacteria  and  molds. 

Fruits  and  vegetables  are  heated  to  kill  the  germs  and 
then  sealed  up  tight  in  cans.  Even  then  mold  often 
grows  on  top  of  the  food  in  the  can  because  the  lid  and 
can  were  not  kept  in  boiling  water  the  ten  minutes  nec- 
essary to  kill  the  spores  of  mold.  The  best  plan  in 
canning  food  is  to  put  it  into  the  jars  and  then  cook  it 
by  placing  the  filled  jars  with  the  covers  screwed  on 
loosely  in  the  oven  or  in  a  wash  boiler  on  top  of  the 
stove.  If  the  boiler  is  used,  an  inch  or  more  of  water  and 
a  cloth  to  prevent  breakage  must  be  put  in  the  bottom. 

The  occasional  poisoning  resulting  from  the  use  of 
canned  fish  or  meat  is  due  to  bacteria  which  were  not 
killed  in  the  cooking.  They  grew  and  excreted  a  poison 
called  ptomaine  in  the  can.  Cooking  does  not  affect  this 
poison  already  formed,  and  boiling  spoiled  products  does 
not  make  them  safe  for  eating.  Food  should  never  re- 
main in  a  metal  can  after  it  has  been  once  opened. 


SUGGESTIONS   FOR   THE   TEACHER  53 

Eggs  may  be  preserved  in  a  good  condition  for  a  period 
of  about  five  months  by  immersing  them  in  a  tin  or  stone  jar 
or  wooden  keg  of  dilute  soluble  glass  (silicate  of  sodium). 
The  pure  soluble  glass  may  be  purchased  at  the  drug  store. 
The  dilute  soluble  glass  is  made  by  adding  one  quart  of 
pure  soluble  glass  to  ten  quarts  of  water. 

Questions 

1.  What  did  the  ancients  believe  as  to  the  origin  of  life?  2.  How 
was  the  cause  of  the  spoiling  of  food  discovered  ?  3.  How  do  molds 
differ  from  bacteria?  4.  Where  are  bacteria  found  and  how  numer- 
ous are  they  ?  5.  About  how  many  bacteria  are  required  to  make  a  mass 
as  large  as  the  head  of  a  pin?  6.  How  rapidly  do  bacteria  multiply? 

7.  What  proves  that    bacteria  can   endure  severe   cold  and   heat? 

8.  Name  some  diseases  due  to  bacteria.     9.  How  may  bacteria  get  into 
the  body?     10.  How  do  bacteria  injure  the  body?     11.  Of  what  use 
are  bacteria  to  the  fruit  and  dairy  industries  ?    12.  Why  could  not  life 
continue  to  exist  without  the  aid  of  bacteria?     13.    What  prevents 
bacteria  from  destroying  food  ?     14.  How  may  the  housekeeper  pre- 
vent mold  from  growing  on  her  canned  fruit  ?    15.  Why  do  canned 
meats  occasionally  poison  people  ? 

Suggestions  for  the  Teacher 

1.  Moisten  well  some  bread  and  then  touch  it  to  the  floor  in  a  few 
places  to  get  the  spores  or  germs  of  mold.     Place  in  a  tightly  covered 
bowl  in  a  warm  room,  and  observe  in  from   three  to  six  days   the 
threadlike   growth  of  mold  on  the  surface  of   the  bread   and  erect 
branches  bearing  at  their  ends  knobs  which  contain  spores. 

2.  Colonies  or  groups  of  bacteria  may  be  secured  as  follows :  Ask 
several  of  the  pupils  to  boil  a  potato  a  half  hour,  and  then  cut  it  into 
halves  with  a  knife  cleaned  in  boiling  water.     Stand  each  half  in  a 
cup  containing  about  a  spoonful  of  water.     Set  the  cups  in  a  room 
being  swept  for  a  minute  or  two,  and  then  cover  with  a  saucer  tightly 
and  keep  in  a  warm  room  about  a  week.     Note  the  white  and  yellow 
slimy  spots  which  are  colonies  or  clusters  of  bacteria  produced  wher- 
ever a  single  germ  fell. 


VII.    MILK 


water 


Why  a  Knowledge  of  Milk  is  Important.  —  Milk  forms 
the  greater  part  of  the  food  of  every  individual  during 
the  first  year  of  life,  and  is  often  the  chief  nourishment 
for  invalids.  Nearly  all  of  the  thousands  of  patients  now 
recovering  from  tuberculosis  are  using  from  one  to  three 
quarts  of  milk  daily.  A  recent  circular  of  the  State  Board 
of  Health  of  New  Jersey  says:  "The 
most  important  element  in  the  enormous 
saving  of  child  life,  which  is  now  occur- 
ring,  consists  in  a  better  understanding 
of  the  dangers  attending  the  use  of 
unclean  milk." 

Professor  Sedgwick,  a  leading  sani- 
tarian, says  :  "  Among  all  the  vehicles 
of  infectious  disease  there  is  perhaps 
none  more  dangerous  than  milk."  The 

bottle  of  milk,  United  States  Census  and  Health  Re- 
showing  of  what  it  tg  ghow  that  5Q  QQQ  children  under 
is  composed. 

five  years  of  age  died  from  the  use  of 
unclean  milk  during  the  years  1900-1904.  Many  other 
children,  as  well  as  adults,  were  made  sick  by  the  use 
of  milk  handled  in  a  careless  way. 

Composition.  —  Cow's  milk  contains  all  five  kinds  of 
food  stuffs.  It  consists  of  87  parts  of  water,  4  parts  of 
proteids,  4|  parts  of  carbohydrates,  3|  parts  of  fats,  and 

54 


FIG.  33.  —  Diagram  of 


FOOD   VALUE 


55 


g  part  of  mineral  matter.  The  chief  proteid  of  milk  is 
casein,  which  is  coagulated  into  a  jellylike  mass  called 
curd  when  milk  becomes  sour.  The  fat  is  in  the  form 
of  miimte  globules  two  or  three  thousand  of  which  are 
required  to  make  a  piece  of  butter  as  large  as  a  pin 
head.  The  carbohydrate  is  milk 
sugar,  much  used  by  druggists  in 
making  pills.  .The  most  important 
of  the  several  minerals  in  milk  is 
lime. 

Food  Value.  —  Milk  is  the  only 
single  article  of  food  that  contains 
all  the  elements  necessary  to  the 
growth  of  the  body.  It  is  a  perfect 
food,  however,  only  for  the"  very 
young,  as  the  substances  required 
for  nourishing  the  adult  are  not 
present  in  the  right  proportions. 
Since  cow's  milk  is  quite  different 
in  composition  from  human  milk, 
water,  cream,  and  sugar  are  usually 
added  to  it  when  it  is  to  be  used 
for  infants. 

It  would  require  about  one  gallon 
of  milk  daily  to  furnish  a  working- 
man  the  necessary  amount  of  tissue-repairing  substance, 
but  the  fats  and  sugars  would  not  be  sufficient  to  give 
the  required  heat  and  energy.  Milk  combined  with 
bread  and  potatoes  makes  a  diet  enabling  men  to  perform 
the  heaviest  work.  A  quart  of  milk  contains  the  same 
amount  of  nourishment  as  three  fourths  of  a  pound  of 


FIG.  34.  —  A  quart  of  milk 
and  a  chicken  weighing 
about  one  pound.  The 
chicken  furnishes  the 
same  nourishment  for 
the  body  as  the  milk, 
but  costs  four  times  as 
much. 


56 


MILK 


beef.  Milk  surpasses  many  foods  in  real  nourishing 
value  not  only  because  it  contains  more  nutrition,  but 
also  because  it  is  almost  completely  digested  and  ab- 
sorbed, whereas  from  one  tenth 
to  one  fourth  of  some  vegetables 
consumed  remain  undigested. 

Economy  in  using  Milk. — 
Milk,  at  six  cents  per  quart, 
forms  a  cheap  nourishment 
when  used  with  other  foods, 
at  the  rate  of  one  quart  per  day. 
An  ordinary  restaurant  lunch 
of  soup,  beef,  potatoes,  turnips, 
bread,  butter,  and  coffee,  cost- 
ing fifty  cents,  will  furnish 
no  more  nutrition  than  a  dairy 
lunch  consisting  of  a  half  loaf 
of  bread  and  a  pint  of  skim 
milk,  costing  five  cents. 

A    pound    of   sirloin   steak, 
/m.35.-A  bottle  of  very  sour  costinff  twenty  cents,  contains 

milk    (photographed),    showing 

what    it    consists    of.    After  about    the    same     amount     of 

Swithenbank  and  Newman.  tisgue    builder    as    two     quarts 

of  milk,  costing  twelve  cents,  but  the  meat  has  only  two 
thirds  of  the  fuel  value  of  the  milk. 

Skim  Milk.  —  When  milk  is  allowed  to  remain  undis- 
turbed in  a  vessel  for  several  hours,  much  of  the  cream, 
containing  the  fat,  rises  to  the  top  and  may  be  removed. 
The  fluid  left  is  called  skim  milk.  It  contains  the  same 
nutriment  as  whole  milk  except  the  fat,  which  is  dimin- 
ished from  three  fourths  to  nine  tenths.  Skim  milk  is 


crvam 


serum 

or 

whey 


casein 

or 

curd 


CREAM 


57 


therefore  an  excellent  food,  as  it  contains  much  proteid 
for  tissue  building  and  considerable  sugar  for  fuel  value. 
Two  and  a  half  quarts  of  skim  milk  have  the  same  food 
value  as  a  pound  of  the  best  lean  beef.  Two  quarts  of 
skim  milk,  costing  six  or  eight  cents,  contain  more  nour- 
ishment than  a  quart  of  oysters,  costing  forty  or  fifty  cents. 


O  .   * 

o  „ 


o        O  O' 


o     * 


o  °0 


Fia.  36.  —Globules  of  fat  hi  skim  milk,  milk,  and  cream,  as  seen  through  the 

microscope. 

About  one  tenth  of  skim  milk  is  composed  of  solids 
which  have  all  the  value  of  whole  milk  for  making  blood, 
muscles,  and  bones,  but  only  half  the  fuel  value. 

Buttermilk  is  soured  milk  from  which  the  fat  globules 
have  been  removed  after  being  collected  by  churning  into 
large  masses  called  butter.  Butter  milk  contains  about 
the  same  nutriment  as  skim  milk.  As  a  food  for  calves 
and  pigs  it  is  worth  at  least  one  cent  per  quart. 

Cream.  — About  one  sixth  part  of  milk  consists  of  cream, 
which  rises  to  the  top  when  a  vessel  of  fresh  milk  is  let 
stand  a  few  hours.  It  is  formed  of  fine  globules  of 


58  MILK 

fat  with  some  milk  entangled  among  them.  Cream  con- 
tains less  muscle-building  substance  than  skim  milk,  but 
is  of  great  value  in  the  treatment  and  cure  of  consump- 
tion. It  costs  less  than  cod-liver  oil,  and  is  quite  as  effec- 
tive in  the  treatment  of 
all  forms  of  tuberculosis. 
Condensed  Milk. — 
This  is  cow's  milk  which 

FIG.  37. -A  tiny  drop  of  milk  prepared  for  ll5lS   been  heated   to   kill 

examination  with  the  microscope,  g,  glass  the  germs  and  to  evapo- 

slide ;  m,  milk ;  c,  thin  piece  of  glass  over  v                     ,,  •    -,       f 

the  milk  rate  ™>Ht  two  thirds  of 

the  water.  Sugar  is 

often  added  to  prevent  the  growth  of  any  germs  remain- 
ing. Some  condensed  milk  is  made  from  skim  milk. 
Condensed  milk  should  not  be  used  regularly  for  feeding 
infants. 

Souring  of  Milk.  —  The  souring  of  milk  is  caused  by 
bacteria.  They  are  everywhere  present  in  the  air,  on  the 
cow,  on  the  hands,  and  in  the  unclean  milk  pail.  Most  of 
them,  when  in  milk  not  kept  cold,  grow  very  rapidly  and 
change  part  of  the  milk  sugar  into  an  acid.  Milk  in  a 
pail  surrounded  by  ice  may  remain  sweet  a  week,  but 
if  left  in  the  warm  living  room  will  turn  sour  in  a  day. 
When  milk  becomes  sour,  there  are  usually  about  250,000 
bacteria  in  each  drop. 

Bacteria  in  Milk.  —  All  milk  sold  contains  bacteria.  The 
number  in  each  drop  usually  varies  from  500  to  90,000. 
They  are  generally  harmless  to  health.  The  milk  while 
in  the  udder  of  healthy  cows  contains  no  bacteria,  but 
thousands  are  present  in  the  lower  part  of  the  canal  of 
each  teat.  The  first  two  or  three  squirts  of  milk,  there- 


BACTERIA   IN   MILK  59 

fore,  washes  out  hundreds  of  them.  The  milk  pail  is 
another  source  of  bacteria.  Wooden  buckets  cannot  be 
kept  clean  and  should  never  be  used.  A  metal  pail, 
rinsed  with  hot  water  and  hung  upside  down,  will  in  most 
cases  after  twelve  hours  contain  more  than  a  million  bac- 
teria. A  single  hair  falling 
from  the  cow  into  the  pail 
has  been  shown  to  have  on  it 
over  1000  bacteria,  and  ever}r 
little  particle  of  dirt  brushed 
off  from  the  udder  adds  from 
a  hundred  to  several  thousand 
germs  to  the  milk.  Others 
come  from  the  unclean  hands 

Of   the  milker.      The   throwing    FIG.  ».- Drawing  of  the  bacteria 

m  the  milk  within  the  tmy  circle 
down    of    hay    or    the   kicking       shown    in    Figure    37,    as   seen 

about  of   dry  straw  has   been      through  the  microscope, 
shown  to  fill   the  air   with   bacteria  to   such  an   extent 
that  over  3000  per  minute  fell  into  the  open  milk  pail. 

Milk  immediately  after  being  drawn  from  the  cow 
usually  contains  from  200  to  2000  germs  in  every  drop, 
depending  upon  the  cleanliness  of  the  milker,  the  cow, 
the  pail,  and  the  stable.  Feeding  the  cows  dry  hay  or 
cleaning  the  stables  just  before  or  during  milking  will 
quadruple  the  number  of  germs  in  the  milk.  Persons 
neglecting  to  wash  the  hands  thoroughly  before  milking 
may  infect  the  milk  with  the  germs  of  scarlet  fever,  ton- 
silitis,  diphtheria,  or  typhoid  fever.  The  following  table 
gives  clear  evidence  that  in  warm  milk  the  bacteria  grow 
nearly  a  million  times  as  fast  as  in  milk  kept  in  a  cool 
cellar  or  in  cold  spring  water. 


60 


MILK 


DEVELOPMENT  OF  BACTERIA  IN  A  DROP  OF  MILK 


BACIEKIA  IN 
FRESH  MILK 

AFTER  9  HR. 

AFTER  24  II  K. 

AFTER  48  HR. 

TEMPERATURE      AT 
WHICH  MILK  WAS 
KEPT 

1500 

250,000 

1,000,000,000 

unknown 

summer  heat,  94° 

1500 

30,000 

200,000 

1,000,000,000 

living  room,    68° 

1500 

3,000 

10,000 

2,000,000 

cool  cellar,      55° 

1500 

1,600 

2,000 

16,000 

refrigerator,    45° 

1500 

1,550 

1,600 

2,500 

packed  in  ice,  35° 

How  to  produce  the  Best  Milk.  —  The  stable  should  be 
well  lighted  and  have  enough  openings  to  admit  plenty  of 
fresh  air.  Except  in  very  severe  weather  the  cows  ought 
not  to  remain  in  the  stables  between  the  milkings,  because 
plenty  of  fresh  air  prevents  tuberculosis.  The  floors 
should  be  cemented  and  kept  clean,  and  the  loose  hair  and 
dirt  removed  from  the  cows  an  hour  before  each  milking. 
The  udders  can  be  cleaned  with  a  damp  cloth.  Only  tin 
or  agate  pails,  washed  with  cold  water  and  then  with 
boiling  water  and  soda,  are  to  be  used.  Neither  a  cloth 
nor  the  hands  should  touch  the  inside  of  a  milk  receptacle 
after  it  has  been  rinsed  well  with  boiling  water.  The 
milker  should  wash  his  hands  thoroughly  just  before 
milking.  Bacteria  and  dirt  may  be  still  further  excluded 
by  laying  a  piece  of  cheese  cloth  across  the  mouth  of  the 
pail  and  milking  through  it.  Milk  thus  produced  brings 
from  ten  to  fifteen  cents  per  quart  in  the  market,  and  will 
make  the  highest  quality  of  butter. 

Care  of  Milk.  —  Although  most  of  the  market  milk  con- 
tains nearly  10,000  bacteria  in  each  drop,  milk  produced 
in  the  way  described  above,  and  cared  for  properly, 


CARE   OF   MILK 


61 


contains  only  from  100  to  180  bacteria  per  drop.  Such  milk 
will  remain  sweet  four  days  in  an  ordinary  cellar  during 
July.  The  certified  milk  which  is  approved  by  medical  soci- 
eties in  cities  usually 
contains  less  than  500 
germs  per  drop  and 
no  bacteria  which 
will  produce  disease. 
Straining  the  milk 
immediately  after 
milking,  through  one 
or  two  thicknesses  of 
cheese  cloth  and  a 
thin  layer  of  absorb- 
ent cotton,  will  re- 
move the  finest  par- 
ticles of  dirt  and  FIG.  39.  —  A  dish  with  a  thin  layer  of  beef  broth 
many  bacteria.  It  Je"y,  in  which  most  bacteria  will  grow.  A  fly 

is     said     that     300 

pounds    of    dirt    are 

consumed     daily    in 

the  milk  supplied  to 

New  York.    As  soon 

as  strained,  the    milk   should   be   cooled   by  means  of  a 

patent  cooler  or  by  placing  the  cans  in  cold  water  and 

stirring   several   times   for   a   few   minutes.       It   should 

then  be  kept  in  a  clean  cold  room  free  from  flies  and  all 

odors. 

Milk  ought  to  be  sent  to  market  in  glass  bottles  sealed 
with  paraffined  pieces  of  pasteboard.  The  thousands  of 
germs  carried  on  the  feet  of  flies  and  blown  with  the  dust 


was  allowed  to  walk  around  on  the  jelly  a 
few  minutes,  and  wherever  it  left  a  germ  from 
its  feet  it  grew  to  form  a  cluster  or  colony  of 
germs  within  a  day  or  two.  Each  white  spot 
is  a  colony  containing  millions  of  bacteria 
which  would  have  grown  in  much  the  same 
way  if  the  fly  had  carried  them  into  the  milk. 


62  MILK 

into  the  milkman's  measure  are  then  avoided.  Many 
of  these  germs  come  from  spittoons  and  the  filth  in 
gutters.  I  have  found  as  many  as  800  bacteria  per 
minute  falling  upon  an  area  equal  to  the  opening  into 
an  ordinary  milk  measure.  Cream  rises  quickly  on  milk, 
and  unless  it  is  bottled  as  soon  as  milked,  one  customer 
will  receive  more  and  another  less  than  the  correct  pro- 
portion of  cream. 

Adulteration.  —  Before  the  enactment  of  the  pure  food 
laws  and  the  appointment  of  inspectors,  a  considerable 
amount  of  the  milk  in  every  town  and  city  was  adul- 
terated with  water,  and  had  added  to  it  chemicals  to 
make  it  remain  sweet.  It  is  a  crime  to  add  anything 
whatever  to  milk.  Every  town  should  have  an  in- 
spector to  see  that  sickness  and  death  do  not  occur  on 
account  of  impure  milk.  It  is  responsible  for  much  of  the 
cholera  infantum  and  other  bowel  troubles  of  children. 
In  Rochester,  from  1891  to  1896,  when  no  special  effort 
was  made  by  the  city  to  maintain  a  pure  milk  supply, 
1000  more  children  died  than  during  the  years  1897  to 
1902,  when  every  effort  was  put  forth  to  secure  clean 
milk.  Actual  experience  in  the  city  of  Leeds  shows 
that  among  children  using  pure  milk  about  one  fourth  less 
die  than  among  those  using  the  ordinary  market  milk. 

Diseases  conveyed  by  Milk.  —  Careful  investigations  by 
more  than  a  hundred  men  prove  clearly  that  sore  throat, 
cholera  infantum,  typhoid  fever,  scarlet  fever,  diphtheria, 
and  tuberculosis  have  been  in  many  cases  transmitted  by 
means  of  milk.  The  germs  of  all  of  these  diseases  except 
tuberculosis  and  perhaps  scarlet  fever  grow  rapidly  in 
milk  not  too  cold.  It  has  been  shown  that  a  single  germ 


TYPHOID   FEVER   AND   MILK 


63 


of  diphtheria  dropped  from  the  lips  or  hands  into  milk, 
can  in  twelve  hours  produce  over  100,000  of  its  kind. 
The  cow  is  not  subject  to  any  of  these  diseases  except 
tuberculosis,  and  therefore  the  germs  of  the  other  dis- 
eases must  find  their  way  into  the  milk  from  the  water, 
the  hands,  the  clothing, 
the  dust,  or  flies.  Over 
300  epidemics  of  infec- 
tious diseases,  each  af- 
fecting from  10  to  500 
persons,  have  been  caused 
by  milk.  Dirty  cows, 
dirty  stables,  dirty  hands, 
or  dirty  vessels  used  in 
the  production  of  milk 
will  sooner  or  later  bring 
sickness  and  in  some 

Cases    death    to    some    of    FlG"  *>--D*»™g  of  typhoid  germs  as 

seen  through  the  microscope. 

those  using  it. 

Typhoid  Fever  and  Milk.  —  At  Cambridge,  •  Massachu- 
setts, there  was  a  typhoid  epidemic  affecting  73  persons, 
all  of  whom  had  used  milk  from  a  farm  where  the  father 
nursed  his  son  sick  with  the  fever  and  also  did  the  milking. 
At  Elkton,  Maryland,  in  1900,  one  milkman,  whose  wife  as- 
sisted in  caring  for  a  typhoid  patient  and  also  did  the  dairy 
work,  supplied  39  families  with  milk,  and  in  every  home 
from  one  to  three  members  became  ill  with  the  fever. 
In  1903,  in  Palo  Alto,  California,  236  cases  of  fever  re- 
sulted from  the  use  of  milk  part  of  which  came  from  a 
dairy  along  a  stream  known  to  contain  typhoid  germs. 
These  reached  the  water  from  patients  living  on  the  bank 


64 


MILK 


three  miles  above  the  dairy.  The  water  from  the  stream 
was  used  to  wash  the  milk  cans.  Over  200  epidemics  of 
typhoid,  each  affecting  from  10  to  500  persons,  have  been 
traced  to  milk  as  the  source. 

Diphtheria  and  Scarlet  Fever  in  Relation  to  Milk  — 
Over  100  epidemics  of  these  diseases  are  known  to  have 

had  their  source  in  the 
milk  supply.  At  Ashta- 
bula  a  hundred  persons 
were  infected  with  diph- 
theria, by  germs  from  one 
dairy  where  a  man  with 
a  light  case  of  the  disease 
helped  care  for  the  milk. 
In  January  and  February 
of  1907  the  milk  of  one 
company  caused  over  600 
cases  of  scarlet  fever  in 

FIG.  41.  — Intestine  from  child  having  tu-     Boston        and       vicinity, 
berculosis.    The  half  hundred  little  lumps 

are  tubercles  full  of  germs  developed  No  One  who  has  Sllttered 
from  a  few  which  the  child  swallowed.  from  any  of  these  dan- 
Bureau  of  Animal  Industry. 

gerous    diseases    should 

handle  the  milk  until  a  month  after  recovery,  because  the 
germs  sometimes  remain  several  weeks  in  the  system. 

Tuberculosis  and  Milk.  —  Many  cows  have  tuberculosis 
in  a  mild  form.  Very  few  herds  kept  most  of  the,  time 
in  stables  are  free  from  this  disease.  The  recent  govern- 
ment reports  indicate  that  over  1,000,000  cows  in  this 
country  have  tuberculosis,  and  some  of  them  are  shed- 
ding these  germs  into  the  milk,  while  nearly  all  tubercu- 
lous cattle  give  off  the  germs  in  their  excretions. 


PASTEUKIZATION 


There  is  no  longer  any  doubt  that  children  may  acquire 
tuberculosis  by  using  the  milk  of  cows  afflicted  with  this 
disease.  Twelve  girls,  having  healthy  parents,  contracted 
tuberculosis  in  a  young  ladies'  boarding  school  in  Paris. 
Five  died,  and  an  examination  showed  that  the  disease  had 
begun  in  the  intestines.  The  cow  which  had  furnished 
the  girls  with  milk 
was  then  suspected 
of  being  diseased  and 
was  killed.  The  milk 
ducts  upon  being 
opened  were  found  to 
be  badly  affected 
with  tuberculosis. 
Many  similar  cases 
are  now  on  record. 
In  some  cities  as 


FIG.  42.  —  Pasteurizing  apparatus. 


many  as  10  in  every  100  samples  of  milk  examined  con- 
tained the  germs  of  tuberculosis.  It  is  a  crime  to  sell  the 
milk  from  cattle  known  to  be  diseased.  The  only  way  to 
determine  whether  a  cow  has  tuberculosis  is  to  have  an 
expert  use  the  tuberculin  test. 

Pasteurization.  —  When  one  is  not  sure  that  the  milk  to 
be  given  a  child  or  invalid  is  perfectly  fresh  and  clean, 
and  from  healthy  cows,  it  is  wise  to  pasteurize  it.  Pas- 
teurization, so  called  from  Pasteur  the  inventor,  consists 
in  heating  the  milk  twenty  minutes  at  about  160°  Fah- 
renheit. This  renders  all  disease  germs  harmless  and 
kills  most  of  the  souring  germs,  but  does  not  make  the 
milk  less  easily  digestible.  Boiling  renders  the  milk  a 
little  more  difficult  of  digestion  by  a  weak  stomach,  and 

DAT.  PHY8.  —  6 


66  MILK 

changes  the  taste.     Pasteurized  milk  will  remain  sweet 
twice  as  long  as  raw  milk. 

The  easiest  way  to  pasteurize  is  to  place  the  milk  in  a 
quart  fruit  jar  or  an  agate  vessel  having  the  shape  of  a 
fruit  jar.  This  is  then  to  be  set  into  a  vessel  of  boiling 
water  just  removed  from  the  stove,  and  the  milk  stirred 
with  a  clean  spoon  for  ten  minutes.  It  must  then  be 
covered  and  left  fifteen  minutes  longer  in  the  water,  after 
which  it  should  be  cooled  quickly  by  placing  on  ice  or  in 
cold  water.  It  is  necessary  that  the  amount  of  boiling 
water  in  the  teakettle  or  other  vessel  be  four  or  five  times 
as  much  as  the  milk,  and  deep  enough  so  that  its  surface 
will  be  about  on  a  level  with  the  surface  of  the  milk  in 
the  jar.  If  a  glass  jar  is  used,  it  must  be  placed  on  the 
ba^k  part  of  the  stove  a  few  minutes  until  it  becomes 
about  as  warm  as  the  hand  to  avoid  being  broken  by  the 
hot  water.  Pasteurized  milk  has  saved  the  lives  of  many 
infants  and  invalids.  A  special  pasteurizing  apparatus,  as 
shown  in  Figure  42,  may  be  purchased  for  a  small  amount. 

Questions 

1.  Of  what  importance  is  milk?  2.  Give  the  composition  of  milk. 
3.  What  can  you  say  of  the  food  value  of  milk?  4.  By  the  table  on 
page  41  compare  the  food  value  of  milk  and  beef.  5.  Show  that  milk 
at  ten  cents  per  quart  is  a  cheaper  food  than  eggs  at  twenty-four  cents 
per  dozen.  6.  Explain  the  food  value  of  ski  in  milk.  7.  What  is 
buttermilk?  8.  Of  what  value  is  cream?  9.  How  is  condensed  milk 
produced?  10.  Why  does  milk  become  sour  ?  11.  What  are  bacteria? 
12.  How  do  bacteria  get  into  milk  ?  13.  Explain  the  effect  of  tem- 
peratures on  the  bacteria  in  milk.  14.  Give  some  directions  to  be 
observed  in  producing  the  best  grade  of  milk.  15.  What  care  should 
be  given  milk?  16.  Why  should  milk  be  marketed  in  bottles'; 
17.  State  some  facts  about  the  adulteration  of  milk.  18.  What  disease 
germs  grow  after  finding  their  way  into  milk?  19.  How  may  the 


SUGGESTIONS  FOR  THE  TEACHER          67 

germs  of  typhoid  fever  get  into  milk?  20.  Give  facts  showing  that 
no  one  caring  for  patients  with  diphtheria  or  scarlet  fever  should 
handle  the  market  milk.  21.  Give  evidence  showing  that  persons 
may  acquire  tuberculosis  by  drinking  milk  from  tuberculous  cows. 
22.  How  may  milk  be -pasteurized  ?  23.  What  is  the  benefit  of  pas- 
teurization? 

Suggestions  for  the  Teacher 

1.  Ask  the  pupils  to  note  whether  the  milk  used  at  home  leaves  an 
unpleasant  taste  in  the  mouth.     Pure  milk  gives  no  unpleasant  after- 
flavor  reminding  one  of  the  smell  of  a  cow.     Ask  the  pupils  to  observe 
whether  there  is  any  sediment  in  the  milk  pail  or  bottle  after  the 
milk  has  stood  several  hours  and  is  then  carefully  poured  off. 

2.  Ask  some  of  the  pupils  to  put  the  lid  tightly  on  the  milk  can 
at  night  after  washing  it,  and  the  following  morning  note  the  odor,  due 
to  the  fact  that  the  germs  were  not  washed  out  clean.     Babies  fed 
milk  from  such  vessels  often  get  cholera  infantum  or  other  bowel 
trouble,  which  frequently  results  in  death.   Ask  the  same  pupils  to  clean 
the  milk  can  the  next  night  by  rinsing  it  well  with  cold  water  and 
then  washing  it  out  with  boiling  water  and  finally  scalding  it  by 
placing  it  on  the  stove,  with  an  inch  or  two  of  water  in  it,  to  boil  five 
minutes  with  the  lid  on.     Note  the  absence  of  odor  the  following 
morning. 

3.  If  possible,  have  one  of  the  pupils  draw  milk  from  the  clean 
udder  of  a  cow  into  a  scalded  glass  jar,  which  should  be  immediately 
placed  in  a  pan  of  cold  water  and  stirred  with  a  clean  spoon  ten  min- 
utes.   Cover  and  keep  cool,  noting  that  it  will  remain  sweet  twice  as 
long  as  milk  cared  for  in  the  ordinary  way. 


Till.    NARCOTICS  AND   STIMULANTS 

Characteristics.  —  Narcotics  are  substances  which  act  on 
the  system  so  as  to  relieve  pain  and  tend  to  produce 
sleep.  If  taken  in  large  doses,  they  cause  a  person  to 
fall  into  a  kind  of  a  stupor  or  deep  sleep.  The  com- 
monest narcotics  are  tobacco,  alcohol  in  large  doses,  opium, 
morphine,  laudanum,  paregoric,  and  many  of  the  patent 
medicines.  - ; 

Stimulants  are  substances  which  cause  any  organs  of  the 
body  to  act  more  vigorously  than  is  their  custom.  Tea 
and  coffee  are  stimulants  frequently  used.  Neither  nar- 
cotics or  stimulants  are  necessary  to  enable  an  individual 
to  make  the  greatest  success  in  life.  Moreover,  it  is  well 
known  that  persons  not  accustomed  to  the  excessive  use 
of  these  drugs  are  much  healthier  and  happier  than  those 
who  are  slaves  to  them. 

Tobacco  is  a  poison.  Like  other  poisons,  one  may  be- 
come so  accustomed  to  its  use  by  beginning  with  small 
doses  and  gradually  increasing  them,  that  large  quantities 
smoked  or  chewed  have  but  little  apparent  effect  in  older 
persons. 

In  certain  parts  of  Italy  some  of  the  people  have  become 
so  accustomed  to  the  use  of  arsenic  that  they  take  ten 
times  as  much  in  a  single  dose  as  would  be  fatal  to  a 
person  not  in  the  habit  of  eating  this  poison. 

The  active  principle  in  tobacco  is  nicotine.  It  is  this 
which  makes  one  so  sick  and  sleepy  when  he  for  the  first 

68 


HOW   TOBACCO    HARMS  69 

time  smokes  even  an  inch  of  a  cigar  or  takes  one  or  two 
chews  of  tobacco.  Tobacco  consists  of  the  dried  leaves 
of  the  tobacco  plant  grown  extensively  in  the  valley  of 
the  Connecticut  River  and  in  Kentucky,  West  Virginia, 
and  many  other  parts  of  the  South,  as  well  as  in  the  West 
Indies.  It  cannot  be  considered  a  food,  but  it  lessens  the 
feeling  of  hunger  by  its  sleep-producing  effect. 

How  Tobacco  Harms.  —  If  there  is  an  inherited  tendency 
to  cancer,  the  irritation  of  the  membranes  of  the  mouth  by 
the  constant  presence  of  tobacco  is  likely  to  cause  the  dis- 
ease to  break  out  in  that  place.  Catarrh,  hoarseness,  and 
throat  trouble  are  common  among  those  using  tobacco  to 
excess. 

While  a  person  is  chewing  tobacco,  the  salivary  glands 
are  kept  in  a  continual  state  of  activity,  so  that  much 
saliva  is  lost  in  spitting.  As  a  result  the  saliva  that  flows 
when  food  enters  the  mouth  is  of  a  poor  quality,  fails  to 
act  on  the  food  properly,  and  then  indigestion  may  be  the 
consequence. 

The  nicotine  absorbed  by  the  vessels  in  the  membrane 
of  the  mouth  has,  especially  in  the  young,  an  injurious 
effect  on  the  heart.  About  one  fourth  of  all  steady 
smokers  show  an  irregular  pulse  beat.  This  condition 
has  caused  a  large  number  of  candidates  for  the  United 
States  Naval  Academy  to  be  rejected.  Students  in  the 
Naval  Academy  are  no  longer  permitted  to  use  tobacco. 

Alfred  A.  Woodhull,  a  surgeon  in  the  United  States 
Army,  says :  "  Tobacco  degrades  the  tissues  generally,  and 
it  predisposes  to  neuralgia,  vertigo,  indigestion,  and  other 
disturbances  of  the  nervous,  circulatory,  and  digestive 
systems." 


70  NARCOTICS    AND   STIMULANTS 

Cigarettes. — Cigarette  smoking  is  the  most  harmful 
form  in  which  tobacco  is  used.  This  is  not  due  to  the 
presence  of  more  nicotine  or  other  narcotic  drugs.  Ciga- 
rettes are  especially  damaging  to  health  because  it  is  the 
habit  of  those  using  them  to  inhale  the  smoke.  This  act 
carries  the  nicotine  down  into  the  air  spaces  in  the  lungs. 
Here  it  is  much  more  readily  absorbed  than  in  the  mouth. 
The  user  of  cigarettes  is  also  more  likely  to  smoke  to  ex- 
cess than  one  addicted  to  the  cigar  or  the  pipe.  The  use 
of  the  cigarette  makes  one  more  a  slave  to  the  drug,  so  that 
when  he  is  deprived  of  it,  a  longing  desire  takes  possession 
of  him.  He  is  unfitted  for  work  or  for  enjoyment  until 
another  dose  of  the  poison  has  been  administered. 

So  pronounced  is  the  opinion  of  the  best  people  against 
the  use  of  the  cigarette  that  a  number  of  states  have 
passed  laws  prohibiting  their  sale.  The  supreme  court 
of  Tennessee  made  the  following  statement :  "  We  think 
cigarettes  are  not  legitimate  articles  of  commerce,  because 
they  are  wholly  noxious  and  deleterious  to  health.  Their 
use  is  always  harmful,  never  beneficial.  They  possess 
no  virtue,  but  are  inherently  bad,  and  bad  only.  They 
find  no  true  commendation  or  merit  or  usefulness  in  any 
sphere.  On  the  contrary,  they  are  widely  condemned  as 
pernicious  altogether.  Beyond  question  their  every  tend- 
ency is  toward  the  impairment  of  physical  health  and 
mental  vigor." 

Crime  and  Cigarettes.  —  Some  railroad  companies  and 
numerous  other  business  corporations  demanding  workers 
mentally,  physically,  and  morally  sound  refuse  to  employ 
a  person  who  is  a  cigarette  smoker.  The  probation  officer 
at  Kansas  City  said  that  of  90  boys  who  had  been 


PATENT   MEDICINES  71 

put  in  jail  during  six  months  of  1902  all  but  two 
were  addicted  to  the  use  of  cigarettes.  A  police  magis- 
trate in  New  York  declares  that  99  out  of  every  100  boys 
between  the  ages  of  ten  and  seventeen  years  who  come  be- 
fore him  charged  with  crime  have  their  fingers  stained 
with  nicotine  from  cigarettes. 

Opium  and  Morphine.  —  Opium  is  a  sleep-producing  drug 
made  from  the  milky  juice  dripping  out  of  the  cut  fruit 
capsules  of  the  white  poppy.  The  plant  is  grown  in  Asia 
Minor,  Persia,  and  India.  Morphine  is  a  white  powder 
separated  from  the  opium  by  a  chemical  process.  It  is 
four  times  as  strong  as  opium.  Neither  opium  nor  mor- 
phine should  be  taken  except  by  the  advice  of  a  physician. 
Persons  sometimes  begin  the  use  of  these  drugs  to  relieve 
them  from  pain  or  produce  sleep,  and  after  a  few  days'  or 
weeks'  use  are  unable  to  stop  taking  them.  Like  alcohol, 
they  create  an  unnatural  appetite  which  is  only  satisfied 
by  constantly  larger  doses.  Hundreds  of  persons  are 
being  treated  yearly  in  sanitariums  and  otherwise  to  help 
them  break  loose  from  this  terrible  habit  of  using  mor- 
phine and  cocaine.  Cocaine  is  made  from  the  leaves  of 
the  coca  plant.  The  numerous  advertisements  in  the 
papers  stating  that  medicines  will  be  sent  at  slight  cost  to 
cure  the  morphine,  cocaine,  or  alcohol  habit  are  issued  by 
fraudulent  persons  seeking  to  rob  unfortunate  people. 

Laudanum  is  a  mixture  of  opium,  alcohol,  and  water, 
and  is  therefore  a  dangerous  drug.  Paregoric  is  a  com- 
pound of  opium,  alcohol,  camphor,  and  some  other  drugs. 

Patent  Medicines.  —  Most  of  the  liquid  patent  medicines 
are  stimulants  or  narcotics.  Some  have  both  properties. 
The  narcotic  contained  in  many  of  them  is  alcohol. 


72 


NARCOTICS   AND   STIMULANTS 


Nearly  all  contain  more  alcohol  than  beer,  and  many  are 
richer  in  alcohol  than  the  strong  wines.  A  few  have 
nearly  as  much  alcohol  as  whisky  has.  It  is  just  as  dan- 
gerous and  just  as  wrong  to  use  these  patent  medicines  as 
it  is  to  use  wine,  whisky,  or  beer.  The  help  which  these 
nostrums  seem  to  afford  the  sick  is  generally  due  to  the 
alcohol  which  makes  one  feel  good  for  a  time.  Late 


FIG.  43.  —  Diagrams  showing  the  amount  of  alcohol  in  alcoholic  drinks  and  one 
of  the  most  widely  used  patent  medicines  which  has  wrecked  many  lives. 

investigations  have  shown  that  patent  medicines  have 
wrecked  many  lives  and  caused  numerous  untimely 
deaths. 

Soothing  sirups  for  children  contain  some  kind  of 
opiates  which  may  ruin  the  constitution  of  a  child.  Most 
of  the  advertised  remedies  for  coughs  owe  their  soothing 
qualities  to  morphine  or  opium.  Nearly  all  catarrh  pow- 
ders give  temporary  relief  only  because  they  contain  opium 
or  cocaine.  Every  one  should  remember  that  the  constit- 
uents of  the  patent  medicines  claiming  to  cure  all  disease 
are  known  to  our  trustworthy  physicians.  If  these  reme- 


COFFEE  73 

dies  helped  the  sick  without  injuring  the  health,  they 
would  of  course  be  used  by  the  reputable  doctors.  Some 
of  our  best  newspapers  and  magazines,  having  lately 
learned  of  the  worthlessness  and  evil  effects  of  patent 
medicines,  have  refused  to  advertise  them. 

Tea.  —  Tea  consists  of  the  dried  leaves  of  an  evergreen 
plant  grown  in  China.  There  are  two  general  classes  of 
teas,  the  one  being  black  and  the  other  green.  Black  tea 
is  prepared  by  exposing  the  fresh  leaves  to  the  rays  of 
the  sun  and  later  rolling  and  breaking  them  up.  They 
are  then  allowed  to  ferment,  after  which  they  are  again 
exposed  to  the  sun  and  then  dried  in  the  oven. 

In  preparing  green  teas,  the  leaves  are  withered  by  heat 
or  steamed,  then  broken  up  and  sweated  in  bags,  and 
finally  roasted.  For  general  use  black  tea  is  preferable  to 
green  tea  because  the  tannic  acid  in  it  is  less  soluble. 
Tannic  acid  delays  digestion,  and  on  this  account  green  tea 
used  at  mealtime  may  produce  dyspepsia.  In  order  to 
make  any  kind  of  tea  so  as  to  contain  as  little  tannic  acid 
as  possible,  the  leaves  should  be  placed  in  a  jar  and  have 
boiling  water  poured  on  them.  The  jar  must  then  be 
covered  a  few  moments,  after  which  the  liquid  tea  is  to  be 
poured  off  into  a  clean  vessel. 

Tea  contains  practically  no  nourishment.  The  stimu- 
lating effect  is  due  to  caffein.  The  drinking  of  large 
quantities  of  tea  may  cause  dyspepsia,  heart  trouble,  sleep- 
lessness, and  other  nervous  disorders.  Tea  should  not  be 
used  by  children. 

Coffee.  —  Coffee  is  prepared  from  the  seeds  of  the  coffee 
plant  grown  in  Arabia,  Java,  Costa  Rica,  and  Brazil. 
The  seeds,  often  called  beans,  are  made  ready  for  use  by 


74  NABCOTICS    AND    STIMULANTS 

being  dried  in  the  oven,  then  roasted  and  ground.  A  cup 
of  black  coffee  contains  about  as  much  tannic  acid  and 
caffein  as  a  cup  of  strong  tea. 

It  stimulates  mildly  the  brain  and  heart  and  deepens 
the  respirations.  Coffee  should  not  be  taken  by  children 
or  by  those  in  ill  health,  as  it  tends  to  disturb  digestion, 
and  to  produce  nervousness  and  sleeplessness. 

Chocolate.  —  Chocolate  is  made  by  grinding  to  fineness 
the  kernels  of  the  roasted  seeds  of  the  cacao  tree.  Chocolate 
contains  a  considerable  amount  of  fat,  starch,  andproteids, 
and  on  this  account  it  makes  a  nutritious  drink.  It  also 
contains  a  small  quantity  of  a  mild  stimulant  which  has 
little  effect  on  the  body.  Cocoa  differs  from  chocolate  in 
that  it  has  been  deprived  of  a  portion  of  its  fat  and  has 
been  more  finely  pulverized.  It  is  an  excellent  drink  for 
children  and  those  recovering  from  illness. 

Alcoholic  Beverages.  —  Alcohol  is  such  a  health  de- 
stroyer, has  ruined  so  many  homes,  and  resulted  in  so 
much  crime  and  poverty,  that  an  entire  chapter  is  later 
devoted  to  the  subject.  While  it  is  true  that  an  adult 
can  occasionally  take  a  drink  of  wine,  beer,  or  whisky 
without  injury  to  health,  yet  there  is  always  the  probability 
that  he  may  before  he  is  aware  of  it  develop  the  alcohol 
thirst  now  affecting  over  1,000.000  people  in  this  country. 
These  drinks  often  wreck  not  only  the  body  but  also  the 
character. 

Questions 

1.  How  does  a  narcotic  differ  from  a  stimulant?  2.  Name  some 
narcotics  and  stimulants.  3.  From  what  is  tobacco  made?  4.  How 
does  tobacco  injure  the  health  ?  5.  Give  evidence  showing  that  tobacco 
is  injurious  to  the  young.  6.  Why  is  the  cigarette  more  harmful  than 
the  pipe  or  cigar?  7.  Why  have  some  states  made  laws  preventing 


SUGGESTIONS  TO  THE  TEACHER          75 

the  sale  of  cigarettes?  8.  What  evidence  is  there  that  cigarettes  make 
criminals?  9.  Why  should  one  never  use  opium  or  morphine  except 
on  a  physician's  prescription?  10.  State  some  facts  about  patent 
medicines.  11.  Explain  the  danger  in  using  soothing  sirups  and 
catarrh  powders.  12.  How  is  tea  prepared  for  the  market  ?  13.  What 
is  the  proper  method  of  making  tea?  14.  Of  what  use  are  tea  and 
coffee  ?  15.  In  what  way  does  cocoa  differ  from  chocolate? 

Suggestions  to  the  Teacher 

1.  Boil  for  ten  minutes  an  ounce  of  tobacco  in  a  half  pint  of  water. 
Place  in  the  tobacco  tea  thus  made  an  earthworm,  a  tadpole,  or  a  snail, 
and  note  how  soon  it  becomes  unconscious  from  the  narcotic  effect  of 
the  tobacco. 

2.  Ask  some  of  the  children  to  make  tea  at  home  by  boiling  the 
leaves  in  water,  and  then  make  another  cup  of  tea  by  merely  pouring 
boiling  water  on  the  leaves.     Note  the  difference  in  taste. 

3.  Assign  to  several  members  of  the  class  the  preparation  of  brief 
reports  on  the  ingredients  and  use  of  certain  harmful  patent  medi- 
cines.    Information  may  be  obtained  from   a  booklet,   The  Great 
American  Fraud,  referred  to  on  page  13. 


TX.     THE   DIGESTIVE   SYSTEM 

THE   ALIMENTARY   CANAL 

THE  general  cavity  within  the  body  is  divided  into  two 
parts  by  the  diaphragm,  which  is  a  dome-shaped  sheet  of 
muscle  and  tendon.  Above  the  diaphragm  is  the  thoracic 
cavity,  surrounded  by  the  ribs  and  other  bones  and  also 
muscles  forming  the  thorax.  It  contains  the  heart,  lungs, 
esophagus,  and  large  blood  vessels.  Below  the  diaphragm  is 
the  abdominal  cavity,  surrounded  by  structures  constituting 
the  abdomen.  It  holds  the  stomach,  liver,  spleen,  pancreas, 
kidneys,  bladder,  intestines,  and  many  large  blood  vessels. 
All  the  organs  in  the  body  cavity  form  the  viscera.  They 
are  enveloped  by  a  semitransparent,  glistening  membrane, 
named  serous  membrane  because  of  the  colorless  fluid,-  the 
serum,  which  it  extracts  from  the  blood.  It  is  this 
fluid  which  allows  the  organs  to  move  freely  against  one 
another  without  friction.  The  serous  membrane  of  the 
thoracic  cavity  is  known  as  the  pleura,  while  that  in  the 
abdominal  cavity  is  called  peritoneum. 

Parts  of  the  Digestive  System.  —  The  collection  of 
organs  used  in  grinding,  mixing,  dissolving,  and  otherwise 
changing  the  food  so  as  to  render  it  capable  of  being 
absorbed  by  the  blood,  together  with  the  canal  used  in 
carrying  the  rejected  remnants  of  the  food  out  of  the  body, 
constitutes  the  digestive  system.  It  consists  of  two  chief 
parts,  the  alimentary  canal  and  the  assisting  glands  of 
digestion. 


THE  MOUTH 


77 


The  divisions  of  the  alimentary  canal  are  the  mouth, 
pharynx,  esophagus,  or  gullet,  stomach,  and  the  coiled 
tube  called  the  intestines  filling  up 
much  of  the  abdominal  cavity  be- 
low the  liver  and  stomach  (Fig.  44). 
The  assisting  glands  are  for  the  pur- 
pose of  secreting  from  the  blood  a 
liquid  for  softening  and  dissolving 
the  food  so  that  it  may  be  taken  into 
the  tissue.  They  are  the  salivary 
glands,  forming  the  saliva  or  spit, 
and  the  liver  and  pancreas,  adjacent 
to  the  stomach. 

Mucous  Membrane.  —  All  sur- 
faces exposed  to  the  air  are  covered 
with  one  or  more  layers  of  epithelial 
cells.  If  the  surface  is  not  freely 
exposed,  so  that  it  may  be  cleansed 
by  air,  sunshine,  and  washing,  the  / 

cells  have  the  power  to  make  from  Fl°;  ^--Diagram  showing 

the  relations  of  the  organs 

the  blood  a  thin,  slippery  substance 
called  mucus  to  serve  as  a  cleanser. 
Such  mucus-secreting  cells,  with 
the  thin  layer  of  underlying  con- 
nective tissue,  form  mucous  mem- 
brane  (Fig.  45).  It  lines  the  entire 
alimentary  canal  and  all  other 
tubes  of  the  body  touched  by  air. 

The  Mouth.  —  The  important  organs  in  the  mouth  are 
the  tongue  and  teeth.  The  tongue  is  composed  of  several 
muscles  covered  with  mucous  membrane,  and  is  used  in 


of  the  hody  cavity,  viewed 
from  the  side.  a.  vermi- 
form appendix;  c,  spinal 
column  inclosing  the  spinal 
cord;  d,  diaphragm;  e, 
esophagus ;  i,  the  great  vein, 
or  vena  cava  ;  k,  kidney; 
lu,  lung;  li,  large  intestine ; 
p,  pancreas;  s,  spleen;  tt 
trachea;  M, ureter;  v, vena 
cava. 


78 


THE    DIGESTIVE   SYSTEM 


speaking  and  in  moving  the  food 
about  in  masticating.  In  the  adult 
there  are  32  teeth,  eight  being  in 
either  half  of  each  jaw.  Because  of 
their  chisel  shape,  the  two  front  ones 
in  the  half  of  each  jaw  are  called 
incisors.  The  next  one  is  the  canine, 
the  two  following  are  the  premolars, 
or  bicuspids,  and  the  three  farthest 
back  are  the  molars. 

The  incisors  are  for  the  purpose  of 
Fia.  45.  —  Section  across    cutting  the   food,  while  the  molars, 

a   mucous    membrane,     with    their    j  flat    grinding    sur. 

showing  blood  vessels. 

Magnified,  e,  epithelial    faces,  serve  to  crush  it.     The  teeth 
are  set  firmly  in  sockets  about  a  half 

inch   deep   in   the   jaw  bones.       The    thickened   mucous 
membrane  in  the  region 
of   the  teeth  forms  the 
gums. 

Milk  Teeth. —An  in- 
dividual living  to  ma- 
turity has  two  sets  of 
teeth.  The  first  set, 
called  milk  or  tempo- 
rary teeth,  are  twenty 
in  number.  The  two 
middle  incisors  of  the 
lower  jaw  usually  appear 

at    the   age  of  from  four  FIG.  46.  —  Mounted  set  of  adult  teeth.  Photo- 

to     eight      months.          A  graphed  in  the  Wistar  Institute  of  Auat- 

3  omy.     Viewed  from  the  right  side,    i,  in- 

feW  weeks  later  the   two  cisors;  c,canine;  p,premolars;m,molars. 


MILK   TEETH 


79 


FIG.  47.  —  Roof  of  the  mouth  of  a  skull  of  a  boy 
18  years  old.  The  last  molars  or  wisdom  teeth 
are  breaking  through.  Photographed  in  the 
Wistar  Institute  of  Anatomy. 


middle     incisors     of 

the  upper  jaw  break 

forth.     At  the   end 

of  the  first  year,  the 

child  should  have  all 

the    eight    incisors. 

The  first  four  molars, 

the  four  canines  or 

eye   teeth,    and    the 

last  four  molars  ap- 
pear   in    the    order 

named,    during    the 

second  year.    About 

the  seventh  year  of 

age    the    permanent    teeth    begin   to   grow   beneath   the 

milk   teeth,  and  by  pressure  against  the  blood  vessels  cut 

off  their  nourishment,  caus- 
ing the  roots  to  be  absorbed, 
so  that  the  milk  teeth  drop 
out  between  the  seventh  and 
twelfth  year,  or  may  be 
easily  pulled,  as  they  are 
held  fast  only  by  mucous 
membrane. 

Sometimes  the  second  set 
of  teeth  do  not  press  in  such 
a  way  as  to  cut  off  the 


FIG.  48.  —  Milk  teeth  of  a  child  from 
the  left  side,  c,  incisors;  i,  ca- 
nines; m,  premolars.  Photo- 
graphed in  the  Wistar  Institute 
of  Anatomy. 


nourishment  of  the  first  set, 
but  appear  at  the  inner  or 
outer  side  of  them.  Unless 
the  milk  teeth  are  then  ex- 


80 


THE   DIGESTIVE   SYSTEM 


tracted,  the  permanent  ones  will  project  and  disfigure  the 
countenance  and  also  be  in  the  wrong  position  for  chew- 
ing. The  twelve  permanent  molar  teeth  are  not  preceded 
by  any  temporary  teeth.  The  first  pair  of  these  in  each 
jaw  appear  at  the  age  of  six  years ;  the  second  pair 

during  the  twelfth  or 
thirteenth  year  ;  and 
the  last  pair,  called 
the  wisdom  teeth,  break 
through  between  the 
seventeenth  and  twenty- 
fifth  year  of  life. 

Structure  of  a  Tooth. 
-  The  part  of  a  tooth 
above  the  gum  is  the 
crown,  the  part  below 
the  gum  is  the  root,  or 
fang,  and  the  constricted 
region  between  these  two 
parts  is  the  neck.  The 

teeth.  a,e,  n,  I,  and  i  ready  to  break  hard  interior  part  of  a 
through  the  gum.  Photographed  in  the  tooth  js  the  dentine, 
Wistar  Institute  of  Anatomy. 

which  is  a  bonelike  sub- 
stance. The  crown  is  covered  with  a  very  hard,  glisten- 
ing substance  known  as  enamel,  while  the  surface  layer 
of  the  fang  is  cement.  The  small  cavity  within  the 
tooth  is  filled  with  pulp,  which  is  a  soft  mass  of  fatty 
material,  together  with  blood  vessels  and  nerves  entering 
at  the  tip  of  the  root.  The  two  large  tusks  of  the  elephant 
used  for  ivory  are  the  overgrown  incisor  teeth  made  of 
very  compact  dentine. 


FIG.  49. —  Part  of  a  skull,  with  the  side 
of  the  jaw  bone  cut  away  to  show  the 


CARE   OF    THE   TEETH 


81 


Care  of  the  Teeth.  —  There  are  always  living  in  the 
mouth  several  kinds  of  bacteria,  some  of  which,  when 
present  in  large  num- 
bers, cause  the  teeth  to 
decay.  Therefore  the 
teeth  should  be  brushed 
twice  daily  with  a  brush 
dipped  in  warm  water.  A 


FIG.  50.  —  Section  through  a 
tooth,  a,  crown;  b,  neck;  c, 
fang ;  d ,  pulp  of  blood  vessels 
and  nerves ;  e,  dentine ;  /, 
enamel ;  g,  cement ;  h,  nerve. 


FIG.  51.  —  Section  from  before  backward 
through  the  front  part  of  the  bead. 
ad,  Adam's  apple,  or  cartilage  of  the 
larynx ;  an,  nostrils,  or  anterior  nares ; 
be,  mouth;  ep, epiglottis;  e,  Eustachian 
tube;  n,  soft  palate;  pn,  posterior 
nares;  ph,  pharynx;  fa,  larynx;  oe> 
esophagus;  sc,  spinal  cord;  se,  part 
of  the  septum  turned  up;  sp,  dividing; 
the  nostrils;  tr,  trachea;  tn,  tonsil 
partly  hid  by  the  uvula;  v,  is  just 
above  the  vocal  cord. 


The  removal,  after  eating,  of  the  particles  of  food  cling- 
ing to  the  teeth,  by  means  of  a  strong  thread  or  wooden 
toothpick,  will  help  much  in  preventing  decay.  A  metal 
pick  should  never  be  used,  as  it  is  likely  to  break  or 

DAY.  PHYS.  6 


82 


THE   DIGESTIVE   SYSTEM 


scratch  the  enamel,  and  it  is  this  hard  covering  which 
prevents  the  bacteria  from  entering  the  dentine  to  cause 
decay.  The  enamel  is  often  broken  by  cracking  nuts  or 
biting  other  hard  substances. 

The  whitish  material  called  tartar  is  a  limy  deposit  from 

the  saliva.  It  should 
be  removed  once  or 
twice  a  year  by  a  den- 
tist, who  can  then  dis- 
cover any  cavities  pres- 
ent and  at  once  fill 
them,  thus  stopping 
further  decay.  The 
milk  teeth  as  well  as 
the  permanent  set  fre- 
quently decay  and  need 
to  be  filled.  Poor  teeth 
lead  to  ill  health  in 
many  persons  and  are 
responsible  for  much 
neuralgia  and  indiges- 


52.  —  Front  view  of  the  viscera, 


spleen;   b,  heart;   d,  diaphragm  ;  e,  liver; 


ff,  lung;  Tiy  stomach;    i,  large  intestine; 
j,  small  intestine ;  k,  bladder. 


tion. 


Pharynx  and  Esoph- 
agus. —  The  irregular 
cavity  back  of  the  mouth  and  in  the  throat  region  is  the 
pharynx.  The  passages  conducting  air  through  the  nose 
open  into  its  top  part,  and  from  either  side  a  small  canal 
called  the  Uustachian  tube  leads  up  to  the  middle  ear, 
while  from  the  back  part  extend  the  esophagus  and  larynx. 
The  conical  body  hanging  from  the  soft  palate  forming 
the  roof  of  the  posterior  portion  of  the  mouth  is  the  uvula. 


THE  STOMACH 


83 


An  oval  body  a  half  inch  long  and  buried  in  the  mucous 
membrane  on  either  side  of  the  root  of  the  tongue  is  the 
tonsil.  Its  use  is  unknown.  A 
growth  of  certain  bacteria  on  it 
and  other  parts  of  the  throat 
causes  tonsilitis,  which  may  be 
conveyed  from  one  member  of  a 
school  to  another  by  the  use  of 
a  common  drinking  cup. 

The  pharynx  narrows  into 
the  esophagus  just  back  of  the 
larynx,  whose  large  part  forms 
beneath  the  chin  a  projection 
known  as  Adam's  apple.  The 
esophagus  is  a  half  inch  in  diam- 
eter and  nine  inches  long.  Its 
muscular  coat  aids  in  propelling 
food  from  the  mouth  to  the  V. 

stomach,  and  the  mucous  lining 
secretes  enough  fluid  to  keep  the  FIG.  53.  —  Front  view  of  the 


interior  well  moistened. 

The  Stomach. — The  esophagus 
opens  below  the  diaphragm  into 
the  stomach.  This  is  an  en- 
largement of  the  alimentary 
canal  for  the  purpose  of  hold- 
ing the  foods  from  one  to  five 
hours  while  the  juices  it  secretes 


organs  of  digestion  removed 
from  the*  body,  a,  c,  and  e, 
colon ;  d,  duct  of  the  gall 
bladder:  c?m,  diaphragm;  g, 
gall  bladder;  h,  hepatic  duct 
from  the  liver ;  k,  kidney ;  ltit 
small  intestine;  Iv,  liver;  n, 
opening  of  the  bile  duct  in- 
to the  small  intestine;  oe, 
esophagus;  pn,  pancreas;  r, 
rectum ;  st,  stomach ;  sp, 
spleen ;  vx,  vermiform  ap- 
pendix. 


act  on  them.     It  has  the  form  of 

a  long  hen's  egg,  and  is  capable  of  holding  over  two  quarts. 

Its  muscular  coat,  made  of  involuntary  muscle  arranged  in 


84 


THE   DIGESTIVE   SYSTEM 


three  layers,  keeps  the  food  in  motion  while  the  glands  of 
the  mucous  membrane  force  out  the  gastric  juice.  This 
softens  and  more  or  less  dissolves  the  food,  which  is  re- 
tained the  proper  time  by  a  circular  muscle  forming  the 
pylorus,  the  opening  of  the  stomach  into  the  intestine. 

The  Intestines.  — -  The  small  intestine  is  a  very  much 
coiled  tube  about  25  feet  in  length,  and  is  over  an 

inch  in  diameter.  The 
two  layers  of  involun- 
tary muscle  forming  the 
muscular  coat  serve  to 
move  the  food  along 
and  mix  it  with  the 
secretion  from  the  thou- 
sands of  little  glands 
forming  much  of  the 
inner  or  mucous  coat. 
From  this  coat  millions 
of  minute,  fingerlike  processes,  the  villi  (Fig.  61),  no 
thicker  than  a  hair  and  one  sixteenth  of  an  inch 
long,  project  and  take  up  the  nourishing  portions  of  the 
food. 

The  small  intestine  leads  by  a  valve  into  the  large 
intestine  at  the  lower  right  side  of  the  abdominal  cavity. 
The  colon  and  rectum  are  the  main  parts  of  the  large 
intestine. 

Vermiform  Appendix.  —  The  vermiform  appendix  is  a 
blind  tube  projecting  from  the  large  intestine.  It  is  as 
large  around  as  a  lead  pencil  and  from  one  to  six  inches  in 
length.  Its  cavity  is  scarcely  larger  in  diameter  than  the 
head  of  a  pin,  so  that  it  sometimes  becomes  clogged  up 


FIG.  54.  — The  small  intestine  joining  the 
large  one.  ap,  vermiform  appendix;  c, 
beginning  of  the  large  intestine;  co, 
colon ;  sm,  small  intestine. 


THE   NATURE   OF   A   GLAND 


85 


with  material  from  the  intestine.  This  may  cause  a  very 
rapid  growth  of  the  bacteria  present,  and  as  a  result  the 
organ  becomes  inflamed  and  often  must  be  removed  to 
prevent  the  bacteria  from  eating  through  into  the  abdomi- 
nal cavity.  This  inflammation  of  the  appendix  is  called 
appendicitis. 

The  appendix  has  no  function  in  man  at  present,  but 
long  ago,  in  prehis- 
toric times,  it  was 
wider  and  longer,  and 
then  was  perhaps  of 
service  in  digestion, 
as  is  the  case  now  in 
the  rabbit,  ground- 
hog, and  cow. 

DIGESTIVE  GLANDS 

The  Nature  of  a 
Gland.  —  A  gland  is 
a  simple  tube  lined 
with  cylindrical 
cells,  or  a  collection 
of  such  tubes,  all 

,  .   ,  ,      FIG.  55.  —  Diagram   of    a    gland,    c,  alveolus, 

OI      which      may     be      or  enlarged  end  of  tube;  i,  common  duct  to 


carry  off  the  secretion  made  by  the  cells  from 
that  part  of  the  blood  passing  through  the 
walls  of  the  capillaries;  a,  arteries;  v,  veins. 


branches  of  the  one 

main   tube   called   a 

duct.     The    purpose 

of  a  gland  is  to  manufacture  some  special  material  from 

the  blood.     The  thousands  of  gastric  glands  in  the  walls 

of  the  stomach  and  the  intestinal  glands  of  the  intestines 

are  simple  or  slightly  branched  tubes  too  small  to  admit 


Sb  THE   DIGESTIVE   SYSTEM 

a  hair.    Nearly  all  mucous  membrane  contains  in  it  glands 

for  secreting  mucus  with  which  to  moisten  the  surface  and 

prevent  the  entrance  of  germs. 

Salivary  Glands.  —  Three  pairs  of  very  richly  branched 

salivary  glands  pour  their  secretions  into  the  mouth.    The 

parotid  gland  lying  just 
beneath  the  skin  and  be- 
low the  ear  forms  an 
irregular,  flat  mass 
about  as  large  as  the 
ear.  Its  duct  opens  on 
the  inner  side  of  the 
cheek.  The  submaxil- 
lary gland  is  somewhat 
the  size  and  shape  of  an 
almond,  and  lies  be- 
tween the  lower  jaw 
and  base  of  the  tongue. 

Fi0.56.-Skin  removed  and  Irontpartof  the  Its   duct   °PenS  beneath 

lower  jaw  cut  away  to  show  the  salivary  the  tongue  on  a  papilla 

glands,    pa,  parotid  gland ;  su,  submaxil-  .-11           ,1            i      T 

lary  gland;   ,/,  sublingual  gland;  dt,  duct  V1Slble  to  the  naked  QJQ' 

of  parotid  gland ;  d,  duct  of  submaxillary  The   Sublingual  gland  is 

gland;  t,  tongue.  .,                 ,,                   ,     ,. 

the   smallest,    and    lies 

under  the  tongue  in  front  of  the  submaxillary.  Its 
several  ducts  open  beneath  the  tongue.  The  secretions 
of  these  three  pairs  of  glands,  together  with  the  glands  of 
the  mucous  membrane  of  the  mouth,  form  the  saliva, 
which  acts  on  the  starch  of  food. 

Gastric  Glands.  —  The  mucous  membrane  lining  the 
stomach  is  composed  almost  entirely  of  tubelike  gastric 
glands  arranged  side  by  side  and  held  in  place  by  a  little 


INTESTINAL  GLANDS 


87 


connective  tissue  between  them.  They  yield  pepsin, 
rennin,  and  hydrochloric  acid.  These  substances,  dissolved 
in  a  watery  liquid 
issuing  also  from 
the  glands,  form  the 
gastric  juice  which 
acts  on  the  proteids 
of  the  food. 

Intestinal  Glands. 
—  The  mucous 
membrane  of  the 
intestine  is  com- 
posed largely  of 
simple,  tubelike 
glands  standing 
side  by  side,  with 
their  mouths  open- 
ing at  the  bases  of 
the  villi  which  stick 


FIG.  57. —  Diagram  of  a  tiny  block  of  tissue 
smaller  than  a  pin's  head,  cut  from  the  wall  of 
the  stomach,  a,  mucous  membrane;  c  and  d, 
muscular  coats;  e,  mouths  of  gastric  glands; 
h,  gastric  glands;  i,  capillaries  supplying  the 
gastric  glands  with  blood;  ra,  artery;  nt  vein. 


out  into  the  cavity 
of     the     intestine. 

These  glands  se- 
crete   about    three 

quarts  daily  of  a  watery  fluid  containing  several  products 
of  great  importance  in  digestion. 

The  Liver.  —  The  liver  is  of  a  brownish  red  color,  and 
is  the  largest  gland  in  the  body,  being  about  equal  in  size 
to  the  upper  half  of  the  head.  It  lies  immediately  under 
the  diaphragm.  A  number  of  deep  incisions  separate  it 
into  five  lobes,  each  of  which  is  made  of  thousands  of  lobules 
about  the  size  of  a  pin's  head.  A  lobule  consists  of  several 


88  THE  DIGESTIVE  SYSTEM 

hundred  cells  having  the  power  of  separating  certain 
substances  from  the  blood  and  manufacturing  them  into 
a  dark  green  liquid  called  bile.  This  escapes  from  the 
liver  through  the  hepatic  duct  leading  to  the  small  intes- 
tine near  its  junction 
with  the  stomach. 
A  branch  •  from  the 
hepatic  duct  carries 
the  excess  of  bile 
to  the  gall  cyst,  or 
gall  bladder,  where  it 
is  stored  until  needed 
for  digestion.  A 
most  important  use 

FIG.  58. — Front  view  representing  the  stomach  £  ,,       ,.                ,, 

pulled  up  to  show  the  pancreas,    a,  aorta;  ot  the   llver    cells    1S 

c,  gall  bladder ;   d,  stomach  end  of  the  small  to  act      On      Certain 

intestine;  e,  esophagus;  o,  liver;  sp,  spleen.  «     A,          „      , 

parts     or    the     food 

brought  by  the  blood  vessels  from  the  intestine  and  hold 
some  of  it  in  storage  for  a  time. 

The  Pancreas.  —  The  pancreas  is  a  pinkish  white  gland 
having  somewhat  the  shape  and  size  of  the  little-finger 
half  of  the  hand.  In  butchered  animals  it  is  known  as 
one  of  the  sweetbreads.  It  extends  from  the  curve  of  the 
stomach  end  of  the  small  intestine  across  the  body  back  of 
the  stomach.  Its  cells  form  nearly  a  quart  of  juice  daily, 
which  is  carried  by  numerous  small  ducts  into  a  larger 
tube,  the  pancreatic  duct.  This  enters  the  small  intestine 
with  the  bile  duct.  Sickness  of  certain  kinds  of  cells 
scattered  in  bunches  throughout  the  pancreas  causes 
diabetes,  an  incurable  disease  characterized  by  sugar  in 
the  blood. 


SUGGESTIONS  FOR  THE  TEACHER          89 

Questions 

1.  Name  the  contents  of  the  thoracic  cavity.  2.  What  organs  are 
located  in  the  abdominal  cavity?  3.  What  is  the  peritoneum? 
4.  Name  the  assisting  glands  of  digestion.  5.  Describe  a  mucous  mem- 
brane. 6.  Give  eight  facts  concerning  an  adult's  teeth.  7.  At  what 
age  do  the  milk  teeth  appear?  8.  When  do  the  milk  teeth  give  place 
to  the  permanent  teeth?  9.  Name  the  parts  of  a  tooth.  10.  Give 
some  points  concerning  the  care  of  the  teeth.  11.  Name  the  parts 
seen  in  your  mouth  wide  open  when  you  are  standing  before  a  mirror. 
12.  What  is  a  tonsil  ?  13.  Locate  the  stomach.  14.  Write  five  im- 
portant facts  about  the  intestines.  15.  What  is  a  gland?  16.  Locate 
the  salivary  glands.  17.  Give  three  facts  about  the  gastric  glands. 
18.  Describe  the  liver.  19.  Point  out  the  location  of  the  liver  on  your 
own  body.  20.  State  five  facts  concerning  the  pancreas. 

Suggestions  for  the  Teacher 

1.  Exhibit  a  full  set  of  teeth,  which  may  usually  be  had  for  the 
asking  from  a  dentist.     Crack  a  tooth  open  and  note  the  structure. 

2.  Ask  the  children  to  examine  the  mouths  of  the  younger  ones  at 
home  and  report  what  teeth  are  present  and  whether  any  are  coming 
in  out  of  place. 

3.  The  entire  alimentary  canal  of  a  cat,  squirrel,  or  rabbit  may  be 
removed  from  a  freshly  killed  animal  and  kept  for  demonstration  for 
many  years,  if  placed  in  a  jar  of  formaldehyde  solution  (formaldehyde, 
three  tablespoonfuls,  and  water,  one  quart). 


X.   HOW  FOOD  IS   DIGESTED 

The  Meaning  of  Digestion.  —  When  food  is  taken  into 
the  mouth,  it  is  not  in  such  a  state  that  the  blood  vessels 
are  able  to  absorb  it  and  carry  it  to  the  cells  in  all  parts 
of  the  body.  Dry  food  to  be  readily  swallowed  must  be 
broken  up  and  well  moistened.  The  stomach  is  of  such  a 
nature  that  it  will  usually  not  allow  any  substance  to  pass 
out  of  it  before  the  substance  has  been  softened  and  made 
into  a  liquid  state.  The  food  on  reaching  the  intestine 
is  changed  into  a  more  perfect  solution. 

The  operations  of  chewing,  softening,  dissolving,  and 
otherwise  changing  the  food  so  as  to  fit  it  to  pass  through 
the  cell  walls  into  the  vessels  for  transportation,  constitute 
the  process  called  digestion.  The  changes  produced  in  the 
food  digested  are  due  largely  to  the  ferments  made  by 
the  glands  in  the  walls  of  the  alimentary  canal  and  by  the 
salivary  glands  and  pancreas.  Ferments  are  substances 
formed  by  living  cells  and  are  capable  of  acting  on  food 
without  any  change  taking  place  in  themselves.  About 
a  dozen  kinds  of  ferments  are  generated  in  the  body. 

Mouth  Digestion.  —  The  touch,  taste,  and  odor  of  food 
cause  the  salivary  glands  to  send  forth  an  abundance  of 
saliva.  About  one  pint  is  secreted  daily.  It  contains  the 
important  ferment  which  acts  on  the  starch  of  foods  so  as 
to  change  it  to  sugar.  The  time  required  for  this  trans- 
formation is  from  ten  minutes  to  twenty  minutes  for 

90 


TASTE   AND    ODOR    OF   FOOD 


91 


cooked  foods,  and  from  one  hour  to  two  hours  for  those 
uncooked. 

The  saliva  does  not  continue  to  act  on  the  food  more 
than  an  hour  after  it  enters  the  stomach,  because  the  food 
has  then  become  mixed  with  the  acid  gastric  juice,  which 
stops  the  action  of  the  ferment. 

Importance  of  Thorough  Mastication.  —  Mastication  means 
chewing  the  food.  It  has  been  well  and  truthfully  said 
that  if  every  mouthful  of  food 
were  chewed  for  one  minute,  the 
common  complaint  about  indiges- 
tion would  seldom  be  heard.  Much 
chewing  of  food  produces  much 
saliva  and  a  complete  mixture  of 
the  two,  so  that  the  ferment  may 
reach  every  particle  of  the  starch. 
Moreover,  the  pleasant  taste  and 
odor  of  food,  prolonged  by  mas- 
tication, excite  the  flow  of  the 
digestive  juices  in  the  stomach. 
Gladstone  is  said  to  have  accounted 
for  his  long  life  and  excellent 
health  by  the  fact  that  he  chewed 

each    mouthful    of     food     at     least 

.,  .   ,       ,. 
thirty  times. 

Taste  and  Odor  of  Food.  —  In  the  dozen  or  more  large 
circumvallate  papillae  on  the  back  part  of  the  tongue  and 
in  other  portions  of  the  tongue  and  mouth  cavity  are  mi- 
nute oval  bodies  called  taste  buds  or  organs  of  taste.  From 
each  a  nerve  fiber  leads  to  the  brain.  The  food  which 
excites  these  end  organs  must  be  in  solution,  and  for  this 


._Toview  of  the 

tongue.      I,    circumvallate 
papillae  ;  e,  epiglottis. 


92  HOW   FOOD  IS  DIGESTED 

the  watery  saliva  is  well  adapted.  A  minute  or  two  is 
often  required  to  effect  this  solution,  and  because  of  this, 
food  swallowed  hastily  has  but  little  taste.  Since  any- 
thing pleasant  to  the  taste  stimulates  greatly  the  flow  of 
the  digestive  juices,  it  is  wise  for  one  to  select  delicious 
eatables.  Much  of  the  pleasing  effect  of  taking  food  is 
due  to  the  odor.  Such  articles  as  coffee,  tea,  grapes, 
horse  radish,  and  onions  affect  the  sense  of  smell  much 
more  than  that  of  taste.  This  may  be  readily  determined 
by  holding  shut  the  nostrils  while  chewing  and  swallowing. 

The  Chewing  of  Gum  and  Tobacco.  —  Pepsin  chewing- 
gum,  which  is  widely  advertised  as  a  remedy  for  indiges- 
tion, owes  its  usefulness  not  to  the  pepsin  it  contains  but 
to  the  pepsin  which  it  causes  the  stomach  to  produce. 
The  sweet  taste  and  the  chewing  act  on  the  nerves  con- 
trolling the  flow  of  the  saliva  and  the  gastric  juice.  The 
chewing  of  dry  bread  or  crackers  aids  digestion  quite  as 
much  as  the  use  of  gum. 

The  chewing  or  smoking  of  tobacco  causes  a  great  waste 
of  valuable  saliva,  as  it  is  spit  out  of  the  mouth.  On  this 
account  the  use  of  tobacco  is  an  uncleanly  habit  as  well  as 
an  unhealthy  one,  especially  £or  the  young.  The  stale  odor 
always  clinging  to  the  person  and  clothing  of  the  constant 
user  of  this  weed  is  very  unpleasant  to  most  women  and 
many  men.  Tobacco  not  only  lessens  the  natural  appetite 
for  food  and  the  power  of  digestion,  but  has  such  a  perni- 
cious effect  on  the  health  of  youth  that  the  Minister  of 
Public  Instruction  in  France  issued  a  circular  forbidding 
the  use  of  tobacco  in  the  public  schools. 

Stomach  Digestion.  —  The  food  at  the  first  part  of  a  meal 
is,  in  a  few  minutes  after  entering  the  stomach,  mingled 


MOVEMENTS   OF   THE   STOMACH  93 

with  the  acid  gastric  juice,  but  that  entering  later  is  not 
affected  by  the  stomach  secretions  for  a  half  hour  or  more. 
It  remains  near  the  entrance,  and  the  saliva  from  the 
mouth  continues  its  action.  The  gastric  juice  is  composed 
of  a  watery  liquid  containing  a  small  amount  of  hydro- 
chloric acid,  pepsin,  and  rennin.  The  last  two  are  ferments. 
Pepsin  changes  the  proteids  to  peptones  so  that  they  can 
be  taken  up  by  the  blood  vessels  of  the  intestines.  Ren- 
nin curdles  milk.  The  food,  when  ready  to  pass  from  the 
stomach  through  the  pylorus,  is  similar  to  thick  gravy  and 
is  called  chyme. 

How  the  Gastric  Juice  is  Formed.  — The  5,000,000  mi- 
croscopic tubelike  glands  completely  lining  the  interior  of 
the  stomach  manufacture  from  the  blood  the  gastric  juice. 
The  glands  are  made  to  act  either  by  the  taste  and  odor 
of  food  or  by  the  presence  of  food  in  the  stomach.  At  the 
beginning  of  the  meal  certain  foods,  such  as  cake,  bread, 
and  potatoes,  cause  a  much  less  flow  of  juice  than  soups 
and  meat.  On  this  account  a  small  amount  of  soup  at  the 
beginning  of  the  meal  is  helpful  to  digestion.  As  a  pleas- 
ing odor  and  taste  tend  to  increase  the  amount  of  stom- 
ach secretion,  the  kind  of  food  easily  digested  by  one  per- 
son may  cause  dyspepsia  in  another.  Grief  or  mental 
excitement  tend  to  decrease  the  action  of  the  gastric 
glands. 

Movements  of  the  Stomach.  —  In  order  that  the  food 
may  be  moved  forward  and  mixed  with  the  gastric  juice, 
the  stomach  must  perform  certain  movements.  It  was 
once  thought  that  these  movements  were  of  such  a  nature 
as  to  cause  the  contents  of  the  organ  to  pass  round  and 
round  from  one  end  to  the  other.  Lately  it  has  been 


94 


HOW    FOOD   IS   DIGESTED 


shown  by  the  use  of  the  X  rays  on  man  and  by  experiments 
on  rats  that  no  such  rotary  motion  of  the  food  occurs. 
The  large  end  of  the  stomach  has  little  or  no  motion,  while 
contraction  of  the  circular  fibers  begins  about  the  middle 
arid  extends  toward  the  pylorus,  squeezing  and  mixing 
the  food  with  the  juices.  One  wave  of  contraction  after 
another  begins  at  the  middle  and  progresses  toward  the 

small  intestine,  tending 
to  press  the  contents  of 
the  stomach  into  the  in- 
testine. The  material 
is  prevented  from  leav- 
ing the  stomach  by 
the  contraction  of  a 
ring  of  muscle,  the  py- 

Fia.  60.  -The  stomach,  with  the  circular  lori°  Valv6'  which  re' 
muscle  fibers  removed  from  the  right  half  laXCS  Only  when  pushed 
to  show  the  other  muscular  fibers.  &gainst  by 


Time  Required  for  Digestion.  —  The  length  of  time  re- 
quired for  gastric  digestion  depends  upon  how  well  the 
food  is  masticated,  how  It  is  cooked,  the  kind  of  food,  and 
the  character  of  the  gastric  juice.  The  strength  of  the 
gastric  juice  is  much  greater  in  healthy  adults  than  in  in- 
fants and  invalids.  Observations  on  the  food  in  the 
stomach  have  been  made  through  a  hole  formed  by  a 
gunshot  wound,  and  further  information  as  to  digestion 
has  been  gained  by  pumping  out  the  contents  through 
a  rubber  tube  at  various  intervals  after  certain  kinds 
of  products  have  been  eaten.  The  following  tables  show 
the  time  required  for  the  digestion  of  some  of  the  common 
foods:  — 


USE  OF  FLUIDS   WITH  MEALS  95 

HOURS  HOURS 

Rice,  boiled 1        Beef,  boiled 2| 

Eggs,  raw  and  whipped     .    .   !£      Beef,  roasted 3 

Eggs,  raw 2        Beef,  fried 4 

Eggs,  soft  boiled 3        Oysters,  raw 2$ 

Eggs,  hard  boiled      .     .    .     .   3|      Oysters,  stewed 3£ 

Milk,  boiled 2  Bread,  white   ......  3$ 

Milk,  raw     .    .    .    .'  .    .    .   2£      Bread,  corn 3£ 

Brains,  boiled  .     .     .     .    .    .    If      Mutton,  roasted 3£ 

Potatoes,  roasted      .  >    .    .    2J      Pork,  roasted 3£ 

Beans,  in  pod,  boiled     .    .     .   2£      Cabbage,  boiled 4£ 

Results  of  Overeating.  —  When  the  stomach  is  too  full, 
its  natural  movement  cannot  take  place.  As  a  result,  the 
ga'stric  juice  is  small  in  quantity  and  changed  in  quality 
and  is  not  properly  mixed  with  the  food.  These  conditions 
cause  an  irritation  of  t'Ke  nerve  endings  in  the  lining  of 
the  stomach,  producing  a  feeling  of  sickness.  If  then  the 
pylorus  does  not  allow  the  undigested  food  to  pass,  vomit- 
ing occurs.  Many  headaches  are  due  to  an  overloading 
of  the  stomach.  Eating  more  than  three  times  a  day  is 
likewise  unhealthy  for  any  one  except  invalids  and  chil- 
dren whose  diet  consists  largely  of  milk.  The  digestive 
glands  are  prevented  from  resting,  and  therefore  give  out 
a  weak  juice  of  poor  quality.  Candies  and  other  sweets 
often  cause  digestive  disorders  if  taken  at  any  other  time 
than  at  the  close  of  the  meal. 

Use  of  Fluids  with  Meals.  —  Very  hot  or  very  cold  fluids 
hinder  digestion,  because  they  decrease  the  flow  of  the 
gastric  juice.  The  use  of  more  than  one  glass  of  water  at 
a  meal  is  usually  not  desirable,  as  the  stomach  secretion  is 
liable  to  be  too  much  diluted.  It  is  especially  harmful  to 
wash  the  food  down  the  throat  by  taking  a  swallow  of 
coffee  or  tea  after  every  two  or  three  bites  of  food. 


96  HOW  FOOD  IS   DIGESTED 

A  vast  amount  of  experience  shows  it  is  unwise  to  use 
habitually  beer,  wine,  ale,  or  any  other  form  of  alcoholic 
drink.  The  large  amounts  of  these  narcotics  so  often 
taken  hinder  digestion.  The  Committee  of  Fifty,  who 
recently  studied  this  question,  state  that  chronic  inflam- 
mation and  catarrh  of  the  stomach  are  common  among 
those  using  alcohol  to  excess.  Dr.  Woodhull,  of  the 
United  States  Army,  says:  "  Its  use  in  health  only  disturbs 
health,  leading  to  numerous  diseases.  So  much  ill  health 
ultimately  depends  upon  alcoholic  indulgence  that  the 
habitual  drinker  both  lays  the  foundation  for  serious 
disturbances  and  steadily  builds  upon  it."  The  govern- 
ment reports  of  Switzerland,  where  alcohol  is  moderately 
used,  state  that  one  in  every  ten  deaths  of  men  over  twenty 
years  of  age  results  from  alcohol.  Wine  may  in  rare 
cases  be  of  some  benefit  to  digestion,  but  the  late  work  of 
Horsley  and  Sturge  shows  that  alcohol  enfeebles  the  churn- 
ing action  of  the  stomach  and  thus  delays  digestion. 

Intestinal  Digestion. —  The  most  important  part  of  the 
digestive  process  is  carried  on  in  the  small  intestine.  In 
order  that  the  liquid  chyme  may  be  thoroughly  acted  on 
by  the  juices  in  the  intestine,  it  is  forced  out  by  the 
stomach  in  small  amounts  at  intervals  of  one  or  two 
minutes.  Two  or  three  quarts  of  intestinal  juice  are 
secreted  daily  by  the  microscopic  tubular  glands  forming 
much  of  the  lining  of  the  intestine.  This  juice  contains 
four  ferments,  one  of  which  splits  up  the  proteids,  another 
changes  the  common  sugar  to  grape  sugar,  and  a  third 
stimulates  the  flow  of  the  pancreatic  secretion. 

Pancreatic  Juice.  — The  pancreas  secretes  nearly  a  quart 
of  fluid  daily,  which  contains  the  most  important  of  all 


MOVEMENTS    OF   THE   INTESTINES  97 

the  ferments  for  digestion.  One  changes  starch  to  sugar, 
a  second  transforms  the  proteids  into  peptones,  and  a  third 
splits  the  fats  into  glycerin  and  fatty  acids.  The  acids 
unite  with  some  of  the  alkali  present  in  the  bile  and  other 
juices,  and  thus  form  soap.  In  this  way  the  starch  which 
escapes  the  action  of  the  saliva,  and  also  the  proteids  un- 
changed by  the  gastric 
juice,  are  perfectly  di- 
gested in  the  intestine. 
The  dark  liquid  mass  of 
food  material,  composed 
largely  of  peptones,  soap, 
and  sugar,  is  now  ready 
for  absorption,  and  is 
called  chyle. 

The  Bile.  —  The  bile  is 
a  greenish  yellow  liquid 
which  is  secreted  by  the 
liver  at  the  rate  of  more  FIG.  61.  —  Slice  of  the  wall  of  the  cat's 

,,  .    ,    i    .1          TO™  small   intestine,    i,    villi;    n,  intestinal 

than  a  pint  daily.    When     glands .  m,  muscular  coat.   Magnified, 
there  is  no  food  in  the 

intestine,  it  is  stored  in  the  gall  bladder,  capable  of  hold- 
ing a  third  of  a  teacupful.  The  bile  has  in  itself  no  diges- 
tive power,  but  hastens  the  action  of  some  of  the  other 
juices.  It  also  contains  some  waste  matter  from  the  body. 
When  the  bile  duct  becomes  clogged,  much  of  the  fats 
escapes  digestion,  and  the  bile  then  gets  into  the  blood  and 
produces  a  disease  called  jaundice. 

Movements  of  the  Intestines.  —  The  longitudinal  and 
circular  muscular  coats  serve  to  give  two  movements 
to  the  intestines.  Peristalsis  or  the  peristaltic  movement 

DAY.  PHY8. 7 


HOW  FOOD   IS  DIGESTED 


consists  of  a  wave  of  contraction  of  the  circular  muscle, 
which  passes  along  from  the  stomach  end  onward,  and  thus 
presses  the  food  down  the  canal.  Another  movement  is 
the  swinging  to  and  fro  of  several  folds  of  the  intestine 
by  a  kind  of  rhythmical  contraction  of  the  circular  and 

longitudinal  muscles. 
These  motions  not  only 
propel  the  food  toward 
the  large  intestine,  but 
also  mix  it  thoroughly 
with  the  digestive 
juices. 

The  food  remains  in 
the  small  intestine  from 
five  hours  to  fifteen 
hours,  during  which 
time  most  of  the 
nourishing  part  is  ab- 
sorbed into  the  blood. 
The  refuse  passes  into 
the  large  intestine,  from 
which  it  should  be 
ejected  daily  at  about  the  same  hour.  Failure  in  perform- 
ing this  important  act  regularly  causes  constipation,  which 
results  in  much  ill  health. 

Absorption  from  the  Intestine.  —  More  than  nine  tenths 
of  all  the  food  reaching  the  blood  has  been  absorbed  by  the 
villi  of  the  small  intestine.  There  are  more  than  20,000 
of  them  to  every  square  inch.  Each  villus  is  composed 
chiefly  of  a  layer  of  cylindrical  cells  covering  a  core 
made  of  a  network  of  blood  capillaries  surrounding  a  sin- 


62.  —  Slices  of  the  small  intestine. 
m,  cat;  n,  human.  A  score  of  villi  are 
seen  on  the  intestine  of  the  cat.  The 
four  folds  of  the  mucous  coat  seen  in 
the  human  intestine  bear  dozens  of  villi 
appearing  as  tiny  shaggy  projections 
scarcely  separated  from  one  another. 
Magnified. 


THE  LACTEALS 


99 


gle  vessel  leading  into  the  lacteal  system  (Fig.  63).  The 
food  passes  through  the  epithelial  cells,  and  then  the  fats 
are  taken  up  by  the  lacteal  vessels,  while  the  other  part 
of  the  food  is  absorbed  by  the  blood  capillaries  uniting 
to  form  the  portal 
system  leading  to 
the  liver  (Fig.  64). 

The  Lacteals.  - 
These  vessels  form 
a  part  of  the  lymph 
system,which  serves 
to  return  to  the 
veins  in  the  neck 
that  portion  of  the 
blood  constantly 
oozing  out  of  the 
capillaries  in  all 
regions  of  the  body. 
The  lacteals  consist 

of    millions    of 
nute    vessels 

ning  blindly  in  the 

villi  and  other  parts 

of  the  intestine  and 

uniting  into  a  score 

or   more   of   threadlike  tubes   which    converge    in    their 

course  to  enter  the  lower  part  of  the  left    thoracic  duct 

(Fig.  64).     This  duct  is  a  tube  about  as  large  as  a  lead 

pencil,  lying  in  front  and   to  one  side  of  the  backbone. 

It  leads  into  a  large  vein  in  the  neck.     The  fats,  upon 

entering  the  lacteals,  are  forced  along  by  the  pressure  of 


mi-  FIG.  63.  —  Diagram  of  the  structure  of  a  block 
of  tissue  smaller  than  a  pin's  head,  cut  from  the 
wall  of  the  small  intestine,  a,  mouths  of  the 
intestinal  glands ;  6,  villus  cut  lengthwise  to 
show  the  blood  capillaries  and  white  lacteal 
within;  e,  lacteal  vessel  sending  branches  to 
many  villi;  i,  intestinal  glands ;  m,  artery;  v, 
vein ;  /  and  t,  muscular  coats. 


100 


HOW   FOOD   IS   DIGESTED 


the  moving  intestines,  by  breathing,  and  also  by  the  suc- 
tion in  the  thoracic  duct  caused  by  the  rushing  along  of 
the  blood  past  its  mouth.  If  a  cat  or  dog  be  given  a  meal 
of  rich  milk  and  killed  about  three  hours  later,  the 

numerous  small  lacteal  vessels  will 
appear  white,  because  of  the  fat 
in  them. 

The  Portal  System.  —  The  portal 
system  consists  of  a  large  portal 
vein,  with  its  tributaries  beginning 
in  the  capillaries  of  the  intestine, 
stomach,  and  other  abdominal 
organs,  and  its  branches  ending  in 
the  capillaries  of  the  liver.  The 
capillaries  do  not  actually  termi- 
nate in  the  liver,  but  are  continuous 
with  the  capillaries  forming  the 
hepatic  vein  carrying  blood  away 
from  the  liver.  Through  this 
portal  system  all  the  food  except 
the  fats  are  transported  from  the 
villi  to  the  liver. 

How  Food  passes  through  the 
Intestinal  Wall.  —  Since  the  ali- 
mentary canal  is  merely  a  tube 
through  the  body,  food  while  in  it  is  not  within  the  body 
where  it  can  be  used  by  the  tissues.  The  final  product 
of  digestion  in  the  small  intestine  is  the  chyle,  which 
passes  into  the  villi  by  three  processes:  1.  osmosis,  which 
is  the  tendency  of  two  liquids  of  different  density  sepa-. 
rated  by  a  membrane  to  mix ;  2.  filtration,  which  is  the 


FIG.  64.  —  Diagram  showing 
how  the  food  reaches  the 
heart  to  be  sent  with  the 
blood  to  all  parts  of  the  body. 


FOOD  PASSING  THROUGH   THE  INTESTINAL  WALL      101 


forcing  of  a  liquid  through  a  membrane  by  pressure 
such  as  would  occur  when  the  muscular  walls  of  tbe 
intestine  contract ;  3.  imbibition,  which  is  the  prop- 
erty possessed  by  a,  cell  of  drinking  in  a  liquid  in 
contact  with  it,  somewhat  as  a  sponge  absorbs  water. 

Osmosis  may  be  shown  with  the  egg  experiment  (Fig. 
66).  By  cracking  the  shell  on  the  large  end  of  an  egg 
it  may  be  removed  with- 
out breaking  the  thin 
skin  beneath.  Through 
a  hole  made  in  the  small 
end  of  the  egg  a  knife 
blade  may  be  thrust 
down  to  pierce  the  mem- 
brane around  the  yolk. 
A  glass  tube  is  then  to 
be  pushed  through  the 
small  end  into  the  yolk, 
and  the  tube  firmly 
cemented  to  the  shell 
with  paraffin  or  sealing 
wax  melted  in  place  with  a  hot  nail.  The  egg  is  then 
placed  tube  up  in  a  glass  of  water,  and  propped  up 
with  a  stick  so  as  to  be  only  half  immersed.  In  less 
than  an  hour  enough  water  will  have  passed  through 
into  the  egg  to  force  the  yolk  far  up  in  the  glass 
tube,  but  none  of  the  proteid  of  the  egg  will  have 
been  pushed  through  the  membrane  into  the  water, 
because  proteids  must  be  acted  on  by  the  digestive  juices 
before  they  can  pass  through  a  membrane.  Some  of  the 
salt  in  the  egg  will  have  passed  out  into  the  water. 


FIG.  65.  —  Part  of  the  intestine,  showing  the 
veins  taking  the  food  from  the  villi  to 
the  liver. 


102 


HOW   FOOD   IS   DIGESTED 


How  the  Body  uses  Proteids  and  Carbohydrates Most 

of  the  proteids  are  used  in  rebuilding  the  worn-out  tissues 
of  the  body,  but  some  may  be  oxidized  to  produce  heat. 
It  is  possible  for  a  proteid  to  be  changed  into  fat.  The 
carbohydrates,  before  entering  the 
blood,  are  all  changed  into  sugar, 
which  passes  through  the  villi  and 
veins  to  the  liver.  Here  one  part  of 
it  is  changed  into  animal  starch,  called 
glycogen,  and  is  retained  until  the 
cells  of  the  body  call  for  it.  A 
second  part  of  the  sugar  is  carried 
to  the  muscles,  and  stored,  while  a 
third  part  circulates  in  the  blood,  and 
combines  with  oxygen  to  make  heat. 
As  oxygen  combines  with  sugar  more 
readily  than  with  proteids,  the  sugar 
is  used  for  heat  and  energy  first,  thus 
leaving  the  proteids  for  muscle  re- 
pair. 

Glycogen.  —  The  form  in  which 
plants  store  up  food  is  plant  starch, 
as  seen  in  the  potato.  Grlycogen,  or 
animal  starch,  is  one  form  in  which 
food  is  stored  for  use  within  an 
animal.  After  a  meal  rich  in  car- 
bohydrates nearly  ten  per  cent  of  the  liver  may  con- 
sist of  glycogen.  After  a  period  of  rest  one  per  cent  of 
a  muscle  consists  of  glycogen,  which  is  completely  used 
up  by  an  hour's  exercise.  An  impulse  sent  through 
the  nerve  to  the  muscle  causes  the  oxygen  from  the 


FIG.  66.  —  Egg  experi- 
ment, showing  os- 
mosis. The  shell  is 
removed  from  the 
egg  at  ra  so  as  not 
to  break  the  mem- 
brane lying  close 
within  it.  a,  glass 
tube ;  p,  paraffin ; 
e,  height  to  which 
the  contents  of  the 
egg  were  forced  in 
an  hour. 


HOW   THE  BODY   USES   FATS 


103 


blood  to  unite  with  the  gly- 
cogen  to  produce  the  con- 
traction of  the  muscle.  It  is 
the  starches  and  the  sugars, 
therefore,  that  furnish  the 
energy-making  stuff  for  a 
workingman. 

How  the  Body  uses  Fats.  - 
Fats  pass  into  the  villi  in  the 
form  of  fatty  acids,  soaps,  and 
glycerin.  These  products  then 
unite  at  once  to  form  fat, 
which,  by  the  lacteal s  and 
thoracic  duct,  is  taken  into 
the  veins  in  the  neck  and 
thence  to  the  heart  (Fig.  64). 
From  here  it  is  sent  with  the 
blood  to  all  parts  of  the  body, 
where  it  is  oxidized.  This 
oxidation,  or  burning,  makes 
heat  to  keep  the  body  warm. 
It  is  for  this  reason  that 
people  in  cold  climates  con- 
sume oils  and  much  fat  meat. 
When  more  fat  than  is  neces- 
sary to  furnish  the  required 
heat  and  energy  reaches  the 
tissues,  it  is  stored  in  the 
connective-tissue  cells  to  form 
the  fat  of  the  body.  If 
too  little  food  is  taken  at 


a 


FIG.  67.  —  Connective- tissue  cells 
changing  to  fat  cells,  a,  fat  pass- 
ing from  the  blood  vessel  to  the 
cells ;  6,  where  the  fat  forms  two 
or  three  globules  of  oil  in  each 
cell;  c,  cells  largely  filled  by  a 
single  oil  globule. 


104  HOW   FOOD   IS    DIGESTED 

any  time,  this  stored-up  fat  is  used  to  provide  heat  and 
energy. 

How  to  make  the  Body  Fat.  —  Some  people  are  always  fat, 
whether  they  eat  little  or  much.  In  some  cases,  however, 
the  amount  of  fat  in  the  body  can  be  controlled  by  diet 
and  exercise.  The  fact  that  the  eating  of  fat  makes  body 
fat  has  been  shown  by  feeding  a  dog  with  mutton  fat  for 
a  week,  at  the  end  of  which  time  much  mutton  fat  was 
found  deposited  in  his  tissues.  That  the  carbohydrates 
are  greater  fat  formers  than  fat  itself  has  also  been 
clearly  demonstrated  by  feeding  experiments.  In  order 
to  become  fleshy,  therefore,  one  should  eat  a  great  deal  of 
carbohydrate  food,  considerable  fat,  and  enough  proteid 
to  take  the  place  of  the  tissue  waste.  Rich  milk,  rice, 
potatoes,  fat  meat,  olive  oil,  oatmeal,  and  soft-boiled  eggs 
form  a  diet  that  will  enable  some  persons  to  gain  a  pound 
or  two  weekly.  An  hour  or  more  of  daily  exercise  and 
ten  hours  of  sleep  in  the  open  air  are  also  of  great  help  in 
increasing  the  body  weight. 

One  who  is  too  fat  should  live  largely  on  lean  meat, 
fish,  fruit,  and  salads,  and  take  plenty  of  exercise.  No 
medicines  advertised  to  make  one  fat  or  lean  are  of  any 
value,  and  they  sometimes  produce  serious  results.  The 
fat  retained  in  the  body  is  stored  in  the  connective-tissue 
cells.  These  are  named  fat  cells  when  most  of  their 
contents  consist  of  fat  or  oil. 

Alcoholic  drinks  tend  to  make  the  body  fat,  because 
alcohol  injures  the  cells  producing  oxidation.  The  worn- 
out  cells  are  not  burned  up  and  cast  out  in  the  excretions 
as  they  should  be  in  health,  but  become  fatty  and  hinder 
the  work  of  the  organs. 


SUGGESTIONS   FOR   THE  TEACHER  105 

Questions 

1.  Where  are  ferments  produced  and  what  is  their  use?  2.  How 
does  saliva  affect  food?  3.  Why  should  food  be  well  chewed? 
4.  Give  five  points  relating  to  the  odor  of  food.  5.  Why  is  the  chew- 
ing of  gum  and  tobacco  generally  harmful?  6.  Explain  the  produc- 
tion of  the  gastric  juice.  7.  Describe  the  movements  of  the  stomach. 
8.  Name  the  three  foods  most  quickly  digested.  9.  Name  the  three 
foods  requiring  the  longest  time  for  digestion.  10.  What  frequently 
causes  dyspepsia?  11.  In  what  one  part  of  the  alimentary  canal  are 
all  kinds  of  foods  partly  digested  ?  12.  Describe  the  action  of  the 
pancreatic  juice.  13.  Of  what  use  is  the  bile?  14.  Why  and  how 
do  the  intestines  move?  15.  How  is  the  food  absorbed  from  the  intes- 
tines? 16.  Give  the  use  of  the  lacteals.  17.  Describe  the  portal 
system.  18.  For  what  purpose  does  the  body  use  lean  meat  ?  19.  Of 
what  use  are  starches  and  sugars  ?  20.  Explain  the  use  of  fats  in  the 
body. 

Suggestions  for  the  Teacher 

1.  Ask  one  of  the  boys  to  secure  from  the  slaughterhouse  a  small 
piece  of  intestine  or  stomach.     On  the  cut  edge  of  this  may  be  seen 
the  mucous  coat,  containing  the  glands,  and  the  muscular  coat,  produc- 
ing the  movements  of  the  digestive  organs.     The  villi  are  clearly  seen 
only  in  the  intestine  of  a  dog  or  cat. 

2.  Ask  some  of  the  pupils  to  try  the  egg  experiment,  as  shown  in 
Figure  06. 


XI.    THE   BLOOD 


Parts.  —  The  blood  is  composed  of  a  colorless  liquid, 
the  plasma,  in  which  float  millions  of  round,  platelike  or 
cup-shaped  cells  called  corpuscles.  These  are  two  kinds, 
the  one  being  red  and  500  times  as 
numerous  as  the  other,  which  are  white. 
It  is  the  presence  of  the  red  corpuscles 
which  gives  the  color  to  the  blood. 

The  Red  Corpuscles.  —  These  form 
almost  half  of  the  weight  of  the  blood. 
About  25,000,000  are  present  in  every 
drop  of  blood  as  large  as  the  head  of  a, 
pin.  They  are  easily  seen  by  examining 
with  the  high  power  of  the  microscope 
a  smear  of  blood  made  by  placing  a  drop 
on  a  glass  slide  and  immediately  drawing 

°Ver  H  the  smoothend  of  another  slide 
relative  amounts  of  held  obliquely  to  the  first. 

Hemoglobin,  the  red  coloring  matter, 
is  the  most  important  part  of  the  corpus- 
cle. The  iron  contained  in  the  hemoglobin  enables  it 
to  carry  oxygen  from  the  lungs  to  supply  the  tissues 
in  all  regions  of  the  body.  The  red  corpuscles  also 
transport  about  half  of  the  carbon  dioxide  from  the 
tissues  back  to  the  lungs  to  be  cast  out. 

106 


WHITE   BLOOD   CORPUSCLES 


107 


White  Blood  Corpuscles.  —  There  is  only  one  white 
blood  cell  to  500  red  ones,  and  as  it  is  colorless,  it  is 
not  easily  seen  under 
the  microscope  unless 
stained  with  some  dye. 
Some  of  the  white  cells 
are  of  the  same  size  as 
the  red  ones,  while 
others  are  more  than 
twice  as  large.  Many 
are  capable  of  changing 
their  shape  very  much 
after  the  manner  of  a 
little  one-celled  animal 

living  in  Stagnant  water     FIG.  69.  —  One  white  corpuscle  and  several 

and  called  the  amceba. 
This  amoeba-like  or  amoe- 
boid motion  of  the  white  cells  may  be  seen  by  examining 
with  the  microscope  a  drop  of  the  fluid  taken  from  a 

blister.  This  liquid  is 
the  blood  plasma,  with 
many  white  corpuscles 
which  have  leaked  out 
of  the  minute  blood 
vessels.  The  white 
cells  creep  through  be- 
tween the  cells  forming 

FIG.  70.  —White  blood  corpuscles,  photo- 

graphed  to  show  their  form  when  crawling.      the  walls    Of    the   Capil- 
laries  in    all    parts    of 

the  body.     In  healthy  tissues  they  are  taken  up  by  the 
lymph  vessels  to  be  carried  back  to  the  veins. 


red  ones,  photographed  through  the  mi- 
croscope. 


108 


THE   BLOOD 


Wherever  there  is  inflamed  or  diseased  tissue,  the  white 
cells  are  attracted  in  great  numbers.     They  creep  out  of 

the  capillaries,  and 
often  large  quanti- 
ties are  destroyed, 
and  then  they  form 

most  of  the  ?*•> or 

white  matter,  pres- 
ent in  a  boil  or  other 

FIG.  7i.  -  Diagram  of  a  capillary  network,  show-   suppuration.        The 
ing  the  white  corpuscles  crawling  through  the    white          Corpuscles 

capillaries  to  eat  the  bacteria,'  causing  aboil  at  ra.    ,  , , 

nave     three     uses: 

they  aid  the  villi  in  absorbing  certain  food  from  the  intestine; 
they  have  some  part 
in  causing  the  clot- 
ting of  the  blood; 
and  they  help  pro- 
tect the  body  from 
harmful  germs  by 
devouring  them. 

Birth  and  Death 
of  Corpuscles.  — 
Since  the  coloring 
matter  of  the  bile 
is  derived  from  the 
dead  red  cells,  and 
since  millions  of 
white  corpuscles  are 
being  killed  wher- 
ever pus  is  formed, 
there  must  be  some 


FIG.  72.  —  Diagram  of  the  capillaries  uniting  an 
artery  and  vein.  The  plasma  is  passing  through 
the  walls  of  the  capillaries  to  nourish  the  body 
cells,  after  which  some  of  it  enters  the  mouths 
of  the  lymph  vessels  and  the  rest  returns  to  the 
the  capillaries.  Arrows  show  the  direction  of 
the  circulation 


THE  USE   OF   BLOOD  109 

means  by  which  new  blood  corpuscles  are  rapidly  devel- 
oped. The  chief  place  of  their  birth  has  been  found  to  be 
the  red  marrow  contained  in  the  ends  of  all  the  long  bones, 
and  abundant  throughout  the  interior  of  the  other  bones. 
The  small  white  corpuscles  are  derived  from  the  division 
of  cells  in  the  several  hundred  lymph  glands  scattered 
throughout  the  body.  Experiments  on  animals,  in 
which  millions  of  red  corpuscles  are  lost  by  bleeding, 
show  that  they  are  regained  so  rapidly  that  more  than 
a  thousand  must  be  formed  every  minute. 

The  Plasma. — This  is  the  colorless  part  of  the  blood 
which  is  constantly  filtering  out  of  the  capillaries  for  the 
purpose  of  supplying  the  tissues  with  food.  While  bath- 
ing these  it  not  only  gives  to  them  nourishment,  but 
receives  from  them  ashes  or  waste  products,  such  as  car- 
bon dioxide  and  that  which  becomes  the  chief  solid  in  the 
urine.  Then  these  waste  products  pass  through  the  cap- 
illary wall  into  the  blood,  but  the  escaped  plasma,  which 
is  not  able  to  return  to  the  capillaries,  is  now  called  lymph. 
Nine  tenths  of  blood  plasma  is  water. 

The  Lymph.  —  This  is  the  blood  plasma  filtered  and  dif- 
fused from  its  vessels.  It  occurs  in  all  spaces  within  the 
body  cavity  and  in  the  crevices  between  the  tissues.  It  con- 
tains numerous  white  blood  corpuscles.  Its  purpose  is  to 
convey  material  to  the  tissues  from  the  blood,  and  to  the 
blood  from  the  tissues.  It  is  carried  back  into  the  blood  sys- 
tem by  thousands  of  microscopic  vessels  uniting  into  larger 
and  larger  vessels,  of  which  two  enter  the  veins  in  the  neck. 

The  Use  of  Blood.  —  The  blood  performs  four  functions  : 
It  regulates  the  temperature  of  the  body,  transfers  food 
to  the  tissues,  bears  oxygen  to  the  tissues,  and  transports 


110  THE   BLOOD 

waste  matter  from  all  regions  to  the  organs  casting  it 
out  of  the  body.  The  heat  formed  by  the  active  cells 
in  the  deep  tissue  is  carried  by  the  blood  to  the  minute 
vessels  near  the  surface  of  the  body,  where  the  cool  air 
and  the  evaporating  perspiration  have  a  cooling  effect. 
The  food  is  carried  in  the  plasma  of  the  blood  to  all 
parts  of  the  body.  A  muscle  cannot  contract  without 
oxygen,  the  vital  organs  refuse  to  act  in  the  absence  of 
oxygen,  and  the  brain  refuses  to  give 
orders  if  oxygen  is  shut  off  only  for  a 
minute.  Therefore  the  distribution  of 
this  element  by  the  blood  is  of  prime 
importance.  Life  could  not  continue 
without  the  transportation  of  the  waste 
products  to  the  lungs,  kidneys,  and 

sweat  Slands  for  elimination. 
clot,  c,  floating  in        The  Clotting  of  Blood.  —  As  soon  as 

blood  escaPes  from  the  vessels, it  under- 
goes  a  change  and  becomes  like  jelly. 
This  is  called  a  clot.  It  is  composed  of  all  the  cor- 
puscles entangled  in  a  white  fibrous  substance  known 
as  fibrin.  The  chief  part  of  the  plasma,  much  of 
which  at  first  is  contained  in  the  clot,  gradually  works 
out,  and  appears  around  it  as  a  yellowish  fluid  named 
serum.  If  blood  is  secured  in  a  tall  vessel  from  the 
butcher  shop  and  placed  twenty-four  hours  in  a  cool  room, 
the  serum  will  appear  on  top  of  the  clot.  There  is  no 
fibrin  in  the  blood  while  in  the  body,  but  there  is  a 
proteid  called  filrinogen,  from  which  fibrin  is  formed  in 
shed  blood  through  the  agency  of  a  ferment  not  active 
in  the  blood  vessels. 


PURE  AND   IMPURE  BLOOD  111 

The  fibrin  may  be  easily  separated  from  the  clot  by 
putting  clotted  blood  into  a  muslin  bag  or  enveloping  it  in 
a  handkerchief,  and  then  kneading  or  squeezing  it  five  or 
ten  minutes  under  water.  The  clotting  of  blood  is  very 
important,  as  by  this  means  nature  often  stops  the  flow 
from  a  wound. 

The  Amount  of  Blood.  —  A  full-grown  person  contains 
about  six  quarts  of  blood.  Half  of  this  quantity  may 
be  lost  through  a  break  in  the  vessels  without  causing 
death.  When  one  has  suffered  the  loss  of  much  blood, 
the  lack  of  fluid  in  the  vessels  is  remedied  by  injecting  a 
normal  salt  solution  (7  parts  of  common  salt  to  1000 
parts  of  water)  into  the  veins.  If  pure  water  were  used, 
many  of  the  red  blood  cells  would  be  destroyed,  and  the 
blood  of  another  animal  cannot  be  used  because  it  like- 
wise causes  the  red  cells  to  go  to  pieces. 

Pure  and  Impure  Blood.  —  The  blood  carried  in  the 
arteries,  except  the  artery  leading  to  the  lungs,  is  spoken 
of  as  pure  or  arterial  blood  because  it  contains  very  little 
carbon  dioxide.  It  has  a  rich  red  color,  while  the  blood 
of  the  veins,  called  venous  blood,  is  of  a  bluish  hue,  as  seen 
through  the  skin  in  the  veins  of  the  wrist.  This  color 
is  due  to  the  carbon  dioxide  gathered  from  the  tissues. 
People  wno  feel  weak  and  languid  or  have  pimples  on  the 
face  are  sometimes  told  that  .their  blood  is  bad.  What- 
ever the  condition  of  the  blood  may  be,  it  is  due  to  the 
healthy  or  unhealthy  state  of  the  organs  of  the  body,  be- 
cause the  blood  is  made  by  the  tissues  and  the  impurities 
are  removed  only  by  certain  organs.  Therefore,  when  one 
is  said  to  have  bad  blood,  it  means  that  the  cells  of  some 
organ  are  failing  to  perform  their  task  properly. 


112  T&E   BLOOD 

Bacteria  in  the  Blood.  —  When  the  body  is  in  health,  no 
bacteria  are  present  in  the  blood  except  just  after  a  meal. 
The  germs  may  gain  access  to  the  blood  with  the  food 
taken  in  by  the  villi.  This  is  a  common  occurrence  in 
children.  The  bacteria  present  in  the  food  of  young 
guinea  pigs  have  been  found  to  pass  into  the  blood  in 
large  numbers,  while  in  older  guinea  pigs  very  few  reach 
the  blood.  It  is  therefore  important  that  one  should  not 
eat  food  containing  disease  germs,  such  as  those  of  tuber- 
culosis, sometimes  found  in  milk  and  butter. 

Harmful  germs  may  get  into  the  blood  and  yet  no  dis- 
ease result,  because  the  plasma  has  the  power  to  destroy 
a  few  bacteria  of  almost  any  kind.  This  power  may  be 
greatly  increased  by  the  use  of  vaccines  and  antitoxins,  so 
helpful  in  preventing  smallpox,  hydrophobia,  diphtheria, 
and  tetanus.  The  white  corpuscles  also  destroy  germs. 

The  Spleen.  —  The  spleen  is  a  dark  red  body  somewhat 
oval  in  shape  and  much  flattened,  so  that  it  is  an  inch 
thick  and  four  inches  broad  by  five  inches  longo  It  lies 
on  the  left  side  of  the  body  in  the  abdominal  cavity,  and 
is  partly  covered  by  the  ribs.  Its  function  is  not  known. 
It  enlarges  very  much  a  few  hours  after  digestion,  and 
probably  has  something  to  do  in  making  a  ferment  to 
aid  the  pancreatic  juice  in  digestion.  It  has  no  duct, 
and  whatever  its  product  is,  it  must  go  directly  into  the 
blood.  In  structure  it  is  like  the  lymphatic  glands,  and 
it  probably  has  a  share  in  making  some  of  the  small  white 
blood  corpuscles. 

The  Thyroid  Gland.  —  This  is  a  flat  two-lobed  body 
weighing  two  ounces.  It  lies  in  front  of  the  trachea  below 
Adam's  apple.  It  has  no  duct.  A  dog  from  which  the 


SUGGESTIONS  FOR  THE  TEACHER  113 

thyroid  has  been  removed  is  able  to  live  only  three  weeks. 
Persons  from  whom  the  thyroids  have  been  removed  on 
account  of  disease  are  kept  alive  by  eating  the  thyroids  of 
calves  or  pigs,  or  by  taking  an  extract  prepared  from 
these  glands.  The  exact  use  of  the  thyroid  gland  is  not 
known,  but  its  secretion  is  turned  directly  into  the  blood 
and  has  a  marked  effect  on  the  mind  as  well  as  the  general 
development  of  the  body. 

Questions 

1.  Name  the  parts  of  the  blood.'  2.  Give  five  facts  about  red  blood 
corpuscles.  3.  What  service  do  the  white  blood  corpuscles  render? 
4.  Where  are  the  blood  corpuscles  formed?  5.  How  fast  may  corpus- 
cles be  formed?  6.  What  is  the  nature  and  use  of  blood  plasma? 
7.  State  what  you  know  about  lymph.  8.  What  are  the  chief  functions 
of  the  blood  ?  9.  When  does  blood  clot  ?  10.  How  much  blood  does 
the  body  contain?  11.  How  does  arterial  blood  differ  from  venous 
blood?  12.  Give  some  facts  in  reference  to  bacteria  in  the  blood. 
13.  Point  out  the  location  of  the  spleen  on  your  body.  14.  State  the 
probable  use  of  the  spleen.  15.  Give  the  function  of  the  thyroid 
gland. 

Suggestions  for  the  Teacher 

1.  If  possible,  borrow  a  microscope  and  ask  the  lender  to  prepare 
a  slide  of  blood  so  that  you  may  show  the  corpuscles  to  the  children. 

2.  Ask  the  class  to  observe  the  blood  in  the  veins  of  the  wrist,  and 
explain  why  it  appears  blue. 


DAT.    PHTS.  8 


XII.    THE   CIRCULATORY   SYSTEM 


THIS  system  consists  of  the  heart,  arteries,  capillaries., 
veins,  and  lymphatics.     The  heart  propels  the  blood,  the 

arteries  carry  it  from 
the  heart,  the  veins 
and  lymphatics  re- 
turn it  to  the  heart, 
and  the  capillaries 
connect  the  arteries 
with  the  veins. 

The  Location  of 
the  Heart  —  The 
heart,  composed  of 
involuntary  muscle, 
is  shaped  like  an  egg 
and  has  its  apex, 
or  pointed  end,  di- 
rected downward 
and  toward  the  left 

.  74.—  Organs  of  the  chest,    The  front  part  si(Je     of     the     body, 

of  the  pericardium  is  cut  away.    The  lungs  . 

have  been  slightly  separated,  a,  right  auricle;  «  IS  Surrounded  by 
6,  diaphragm;  e,  left  auricle;  A,  vena  cava;  a  tough  membrane, 
k,  kidney;  n,  right  ventricle;  p,  artery  to  the  . 
lungs;  r,  one  of  the  several  cut-off  ribs;  t,  tne  pericardium,  COH~ 
vena  cava;  u,  arteries  to  head  and  arms;  v,  tainino"  half  a  tea- 
left  ventricle,  f 

cupful  of  lymphlike 

fluid.       This   protects   the    heart   from   injury.      It   lies 
between  the   lungs   and   almost    in    the   center    of    the 

114 


THE   CAVITIES    OF   THE   HEART 


thoracic  cavity,  where  it  is  held  in  place  by  the  great 
blood  vessels  attached  at  the  upper  and  back  part,  and 
also  by  fibrous  tissue  connecting  the 
pericardium  with  the  breastbone. 
The    Cavities   of   the    Heart.  - 
The  heart   contains   four   cavities, 
the   two   upper   and   smaller   ones 
being  called  auricles,  while  the  two 


FIG.  75.  — The  human  heart 
from  in  front,  a,  aorta; 
ao,  aorta  descending  back 
of  the  heart;  c,venacava; 
ca,  carotid  arteries  to  the 
head;  e,  esophagus;  t, 
left  auricle;  nt,  arteries 
to  the  arm ;  p,  pulmonary 
artery;  r,  right  auricle; 
t,  left  ventricle,  tr,  tra- 
chea or  windpipe. 


FIG.  76.  —  Diagram  showing  the 
front  half  of  the  heart  cut  away. 
a,  aorta ;  I,  arteries  to  the  lungs ; 
la,  left  auricle ;  Iv,  left  ventricle ; 
m,  tricuspid  valve  open ;  n,  bi- 
cuspid or  mitral  valve  closed  ; 
p  and  r,  veins  from  the  lungs ; 
ra,  right  auricle ;  rv,  right  ven- 
tricle; v,  vena  cava.  Arrows 
show  direction  of  circulation. 


lower  are  named  ventricles  (Fig.  74).  The  auricles  are  thin- 
walled  sacs  which  receive  the  blood  from  all  parts  of  the 
body  and  pass  it  to  the  thick-walled  ventricles,  whicli  send 


116 


THE   CIRCULATORY    SYSTEM 


it  out  to  the  tissues.  The  cavities  on  the  left  side  of  the 
heart  are  known  as  the  left  auricle  and  left  ventricle,  the 
other  two  being  termed  the  right  auricle  and  right  ven- 
tricle. The  muscular  walls  of  the  left  ventricle  are  more 
than  twice  as  thick  as.  those  of  the  right,  because  the  one 

sends  the  blood  all 
over  the  body,  while 
the  other  sends  it 
only  to  the  lungs. 

The  two  openings 
into  the  right  auricle 
are  the  ascending 
vena  cava  and  the 
descending  vena 
cava.  There  is  no 
opening  between 
the  two  auricles, 
but  a  large  aperture 
guarded  by  valves 
permits  the  blood 
to  pass  from  an 

FIG.  77.  —  Calf's  heart  cut  open,  a  and  ao, 
arteries;  c  and  o,  parts  of  tricuspid  valve; 
v,  right  ventricle ;  e,  cut  wall ;  n,  cut  wall 


auricle  to  the  ven- 
tricle below  it. 


Four    pulmonary 

veins  open  into  the  left  auricle  and  bring  the  pure  blood  from 
the  lungs.  There  is  only  one  artery  leading  from  each  ven- 
tricle. From  the  left  ventricle  the  aorta,  a  great  artery  larger 
than  the  thumb,  carries  the  blood  to  the  body.  From  the 
right  ventricle  the  pulmonary  artery  extends  to  the  lungs. 
The  Valves  of  the  Heart.  —  In  order  that  the  blood  may 
pass  in  only  one  direction  through  the  heart,  four  sets  of 


THE  VALVES  OF  THE  HEART 


117 


valves  are  present.  Between  the  right  auricle  and  ven- 
tricle is  the  tricuspid  valve,  composed  of  three  membranous 
flaps  whose  free  edges 
are  prevented  from 
being  pushed  back  into 
the  auricle  by  the  sev- 
eral tough  cords,  an  inch 
or  two  long,  extending 
from  them  to  the  walls 
of  the  ventricles  (Fig. 
77).  The  free  margins 
of  this  valve,  hanging 
down  into  the  ventricle, 
permit  the  blood  to  pass 
from  the  auricle  to  the 
ventricle,  which  contracts  and  presses  the  blood  against 
the  lower  surface  of  the  flaps.  This  pushes  them  up  and 
together,  thus  closing  the  aperture 
so  that  the  blood  must  pass  out  of 
the  pulmonary  artery. 

The  mitral  or  bicuspid  valve 
guards  the  passage  between  the 
left  auricle  and  left  ventricle. 
It  works  in  the  same  way  and 
exhibits  the  same  structure  as  the 
tricuspid  valve,  except  there  are 
only  two  membranous  flaps. 

In    the    mouth    of    the    artery 


FIG.  78.  —  The  pulmonary  artery  cut  open 
to  show  the  semilunar  valves,  1,  2,  3.  rvt 
right  ventricle. 


FIG.  79. — The  aorta  cut  off 
at  the  heart,  showing  the 
three  somewhat  triangular 
somilunar  valves  closed. 


leading  from  each  ventricle  are  three  half-moon-shaped 
pieces  of  membrane  attached  by  their  convex  sides  only 
so  that  their  free  margins  may  be  pushed  out  to  prevent 


118 


THE   CIRCULATORY   SYSTEM 


FIG.  80. —The  chief  blood  vessels 
of  the  human  body.  On  the  left 
arm  and  leg  the  vessels  are  shown 
as  they  appear  just  beneath  the 
skin.  The  veins  are  in  black, 
a,  location  of  the  heart ;  6,brach- 
ial  artery  and  veins;  c,  carotid 
artery ;  /,  femoral  vessels ;  i, 
iliac  vessels;  .;,  jugular  vein; 
I,  pulmonary  vessels  to  the  lungs ; 
ra,  radial  vessels;  tt  anterior 
tibial;  u,  ulnar  vessels. 


the  backward  flow  of  the 
blood.  On  account  of  the 
shape  of  the  parts,  these  valves 
are  called  semilunar  (Fig-.  79). 

How  the  Heart  Works.  — 
The  auricles  are  filled  with 
blood  at  the  same  time,  and 
then  they  contract  and  push 
the  blood  into  the  ventricles, 
which  at  once  contract  to 
send  the  blood  out  to  the 
arteries.  Then  there  is  a 
pause  of  about  a  half  second, 
while  the  heart  is  filling,  be- 
fore another  contraction  takes 
place.  The  contraction  of 
any  part  of  the  heart  is  called 
a  systole,  and  the  pushing  out 
of  the  walls  while  being  filled 
is  the  diastole.  The  alternate 
contraction  and  expansion  of 
the  walls  of  the  heart  con- 
stitute the  heart  beat,  which 
occurs  about  75  times  per 
minute  in  the  adult  and  140 
times  in  the  young  child. 

Exercise  and  the  Heart.  — 
The  heart  must  beat  faster 
during  exercise  in  order  to 
drive  through  the  lungs  a 
larger  volume  of  blood  to 


HEART   DISEASE 


119 


endothelium 

internal 
elastic  Uu/& 

circular 
musclejibei 


secure  enough  oxygen  to  supply  the  demand  of  the  muscles. 
Every  muscular  contraction  uses  up  oxygen,  and  therefore 
the  greater  the  exercise,  the  greater  is  the  amount  of 
oxygen  needed.  This  need  of  the  muscles  is  carried  by 
the  nerves  to  the  spinal  cord,  where  the  proper  cells  send 
the  order  to  the  heart  to  work 
more  rapidly.  Prolonged  and 
severe  exercise,  such  as  bicycle 
riding  and  running,  if  indulged 
in  frequently,  sometimes  causes 
enlargement  of  the  heart,  re- 
sulting in  serious  trouble. 

The  Pulse.  —  The  pulse  is 
the  wave  of  blood  produced  in 
the  arteries  by  the  heart  beat. 
It  may  be  felt  wherever  an 
artery  runs  near  the  surface,  as 
on  the  thumb  side  of  the  wrist 
or  just  in  front  of  the  ear. 
Sickness  usually  affects  the 
heart  beat,  because  poisons  are 
being  generated  in  the  body, 

and  they  act  on  the  nerves  controlling  the  heart.  On  this 
account,  the  frequency  and  strength  of  the  pulse  furnish 
the  doctor  with  valuable  information  concerning  the 
bodily  health. 

Heart  Disease.  —  Some  form  of  heart  disease  is  a  com- 
mon ailment  in  people  over  sixty  years  of  age,  and  occa- 
sionally in  those  much  younger.  The  census  report  of 
1906  shows  that  more  than  100,000  people  died  of  heart 
disease  in  that  year  in  the  United  States.  Fatty  degen- 


outercoat 


FIG.  81.  —  Small  artery.  Mag- 
nified. Part  of  the  coats  re- 
moved at  one  end  to  show 
structure. 


120 


THE  CIRCULATORY   SYSTEM 


eration  of  the  heart,  caused  by  the  muscle  being  changed 
to  fat,  is  likely  to  affect  fleshy  persons,  and  is  especially 
prevalent  among  beer  drinkers. 

A  most  serious  affection  of  the  heart  is  the  inability  of 
the  valves  to  prevent  the  blood  from  flowing  backward. 

Disease  of  the  valves  often 
results  from  rheumatism, 
scarlet  fever,  and  diph- 
theria. The  medicines 
much  advertised  to  cure 
heart  ailments  are  of  no 
use,  and  should  never  be 
taken  by  those  who  want 
to  live.  A  physician 
should  be  consulted.  The 
very  rapid  and  irregular 
beating  of  the  heart  is 
spoken  of  as  palpitation 
of  the  heart.  It  is  fre- 
quently caused  by  some 
digestive  trouble  in  the 
stomach. 

The  Arteries.  —  The 
vessels  carrying  the  blood 
away  from  the  heart  are 
the  arteries.  Prior  to  the 
seventeenth  century  they  were  thought  to  conduct  air, 
hence  the  name.  They  are  empty  after  death,  and  the 
blood  is  found  in  the  heart  and  veins.  The  walls  of  the 
arteries  are  much  thicker  and  more  elastic  than  those  of 
the  veins.  They  are  made  of  elastic  fibers,  other  con- 


FIG.  82.  —  Microscope  arranged  to  see 
the  blood  circulating  in  the  tail  of  a 
tadpole. 


THE  CAPILLARIES 


121 


nective  tissue,  involuntary  muscle   cells,  and  a  layer   of 
flat  epithelial  cells  within. 

The  chief  artery  of  the  trunk  is  the  aorta,  which  leads 
from  the  left  ventricle,  and  at  once  forms  an  arch  to  pass 
behind  the  heart  down  through  the  body  cavity  in  front 
of  the  backbone.  It 
gives  off  more  than 
thirty  branches  to  the 
trunk  and  the  internal 
organs.  In  the  lower 
part  of  the  abdominal 
cavity  it  divides  into 
a  right  iliac  and  a  left 
iliac  to  supply  the  legs 
with  blood.  From  the 
arch  of  the  aorta  three 
branches  are  given  off 
to  supply  the  arms, 
neck,  and  head.  The 
large  artery  on  either 
side  of  the  windpipe  is  the  carotid,  taking  blood  to  the 
head  and  brain. 

The  pulmonary  artery  is  a  large  vessel  leading  from 
the  right  ventricle  to  the  lungs.  This  is  the  only  artery 
transporting  venous  blood.  All  the  arteries  branch  again 
and  again,  like  the  branches  of  a  tree,  until  the  little 
vessels  are  too  small  to  be  seen  with  the  naked  eye. 

The  Capillaries.  —  The  capillaries  are  the  smallest  blood 
vessels  of  the  body  and  serve  to  connect  the  arteries  with 
the  veins.  A  capillary  is  about  as  long  as  the  diameter 
of  an  ordinary  pin,  while  its  breadth  is  one  fifth  that  of 


FIG.  83.  —  Arteries  dividing  into  capillaries 
in  a  muscle.  Photographed  through  the 
microscope. 


122  THE   CIRCULATORY   SYSTEM 

a  hair.  From  each  terminal  minute  artery  branch  several 
capillaries,  which  reunite  so  as  to  form  a  network  in  all 
regions  of  the  body.  These  vessels  are  so  numerous  that 
a  needle  cannot  penetrate  the  flesh  without  piercing  some. 
The  walls  of  the  capillaries  are  made  of  a  single  layer 
of  epithelium,  so  thin  that  the  oxygen  and  food  in  the 
blood  may  easily  pass  through  while  the  waste  of  the 
tissues  enters  the  blood.  The  capillaries  with  the  blood 
moving  in  them  may  be  easily  seen  in  the 
tail  of  a  tadpole  or  a  small  fish  on  a  large 
glass  slip  put  under  the  low  power  of  the 
microscope  (Fig.  82). 

Use  of  the  Capillaries.  —  Arteries  and 
veins  merely  conduct  blood.  The  capil- 
laries perform  three  functions :  they  con- 
nect the  arteries  with  the  veins ;  they 

allow  the  oxygen»  some   white   cells>  and 
valves,   i,  free    some  plasma  to  escape  among  the  tissues ; 

and  they  let  waste  matter  pass  from  the 
tissues  into  the  blood.  Sufficient  time  is  afforded  for 
the  exchange  of  these  elements,  as  the  blood  flows  very 
slowly  through  the  capillaries. 

The  Veins.  — The  walls  of  the  veins  are  much  thinner 
than  those  of  the  arteries,  but  have  a  similar  structure. 
They  carry  the  blood  to  the  auricles  of  the  heart.  The 
venous  blood  differs  from  the  arterial  in  containing  little 
oxygen  and  much  carbon  dioxide.  The  pulmonary  veins, 
leading  from  the  lungs  to  the  heart,  convey  oxygenated 
blood.  The  two  great  veins  of  the  trunk  are  the  descend- 
ing vena  cava,  bringing  the  blood  from  the  head,  neck,  and 
arms,  and  the  ascending  vena  cava,  returning  blood  from 


LOCATION    OF   THE   VESSELS 


123 


the  trunk,  the  internal  organs,  and  the  legs.  The  large 
vein  on  either  side  of  the  neck  is  the  jugular. 

Within  the  veins,  especially  those  of  the  extremities, 
are  numerous  valves  permitting  the  blood  to  pass  in  only 
one  direction.  The  arteries,  except  at  their  openings  from 
the  heart,  do  not  have  valves.  By  breathing  and  move- 
ment of  the  muscles 
of  the  trunk  and 
limbs,  the  blood 
vessels  are  pressed 
on,  and  their  con- 
tents are  then 
forced  toward  the 
heart,  because  the 
valves  of  the  veins 
permit  the  blood  to 
flow  in  only  one 
direction. 

HOW     the     Blood     FlG-  m'  ~~  ^S10118  where  large  arteries  lie  near 

the  skin. 

Vessels  are  Named. 

—  The  names  of  the  arteries  and  veins,  as  well  as  the 
nerves  supplying  an  organ,  are  usually  derived  from  the 
Latin  name  of  the  organ.  Brachial  is  the  name  of  the 
large  vessels  in  the  arm,  renal  applies  to  the  vessels  of 
the  kidneys,  hepatic  to  those  of  the  liver,  cardiac  to  those 
of  the  heart,  mesenteric  to  those  of  the  intestines,  radial 
to  those  along  the  radius,  and  femoral  to  those  along 
the  femur. 

Location  of  the  Vessels.  —  Most  of  the  arteries  lie  in 
protected  places  deep  beneath  the  muscles.  In  the 
forearm  and  also  in  the  leg  below  the  knee,  two  or  three 


124 


THE  CIRCULATORY  SYSTEM 


routes  are  provided  for  the  blood  to  and  from  the  ex- 
tremities, as  may  be  seen  in  the  figures.  The  brain  is 
a  most  important  organ,  and  there  are  four  different 

channels  provided 
for  carrying  to  it 
the  blood  from  the 
large  vessels  in  the 
chest. 

In  the  limbs  the 
chief  veins,  arteries, 
and  nerves  lie  close 
together  and  usually 
near  the  bone.  An- 
other set  of  veins, 
known  as  superficial, 
lie  just  beneath  the 
skin.  These  may 
be  seen  plainly  in 
the  arm. 

Lymph  Vessels, 
or  Lymphatics. — 
There  are  numerous 
chinks  and  crevices 
among  the  tissues 
called  lymph  spaces. 


FIG.  86.  —  a  is  bluing  injected  through  the  skin  on 
a  cat's  ear,  to  show  how  from  this  lymph  space 
the  many  tiny  lymph  vessels  take  up  the  blue 
material  and  pass  it  on  to  larger  vessels. 


Large  lymph  spaces  exist  within  the  serous  membranes  of 
the  thoracic  and  abdominal  cavities.  From  all  of  these 
spaces  the  lymph  is  conveyed  by  minute  vessels  called 
lymph  capillaries.  They  form  a  thick  network  in  many 
parts  of  the  body.  They  unite  to  form  larger  vessels,  and 
these  combine  to  form  trunks,  of  which  there  are  several 


LYMPH   VESSELS,   OR   LYMPHATICS 


125 


(lac 


extending  up  each  limb  and  downward  from  the  head. 
Those  from  both  legs,  the  left  side  of  the  body,  neck, 
head,  and  left  arm  join  the  left  thoracic  duct.  This  is 
about  the  size  of  a  lead  pencil,  and  extends  from  the  lum- 
bar region  along  the  back  side  of  the  body  cavity  to  unite 
with  the  large  vein  in 
the  neck.  The  trunks 
of  the  right  side  of  the 
body,  right  arm,  and 
right  side  of  head  and 
neck  join  the  very  short 
duct  emptying  into  a 
vein  on  this  side  of  the 
neck. 

Vessels  also  lead 
from  the  internal  organs 
to  the  thoracic  duct. 
Those  extending  from 
the  small  intestine  are 
called  lacteals,  because 

in  addition  to  the  lymph    FlG- 87-  -  The  lymphatics,  or  lymph  ves- 
sels.   The  dark  spots  are  lymph  glands, 
they    convey    the     fatty         or  nodes,  lac,  lacteals ;  re,  thoracic  duct. 

portions    of    the    food, 

appearing  white  like  milk.  The  purpose  of  the  lymph 
vessels  is  to  return  to  the  veins  that  part  of  the  blood 
which  escapes  from  the  blood  capillaries. 

Any  substance  injected  beneath  the  skin  will  be  taken 
up  by  the  lymph  vessels  and  rapidly  distributed  over  the 
system.  Vaccine  germs  and  the  poison  from  a  snake  bite 
are  usually  gathered  up  by  the  lymphatics,  as  are  also  the 
medicines  administered  by  hypodermic  injections. 


126  THE   CIRCULATORY  SYSTEM 

Lymph  Glands,  or  Nodes.  —  These  are  small,  round,  oval, 
or  oblong  bodies,  some  of  which  are  no  larger  than  the 
head  of  a  pin,  while  others  are  a  half  inch  in  diameter. 
They  occur  most  abundantly  in  the  region  of  the  neck  and 
in  a  fold  of  the  peritoneum,  which  holds  the  intestine  in 
place.  Other  groups  are  found  where  the  limbs  join  the 
body  and  behind  the  lungs. 

No  lymph  is  turned  into  the  veins  without  first  passing 
through  one  or  more  lymph  glands,  which  tend  to  with- 
hold the  bacteria  or  other  harmful  substances  from  enter- 


FIG.  88.  —  Lymph  vessels  of  the  finger. 

ing  the  blood.  A  boil  or  other  inflammation  on  the  arm 
may  cause  many  germs  and  so  much  poison  to  be  carried  to 
the  glands  in  the  armpit  that  they  enlarge  and  become 
very  tender  in  their  effort  to  destroy  these  enemies  to 
health.  The  lymph  nodes  are  also  of  use  in  making 
some  of  the  white  blood  corpuscles. 

Cause  of  the  Flow  of  the  Lymph.  —  Lymph  vessels  filled 
with  colored  fluid  may  be  recognized  by  their  knotted  ap- 
pearance, due  to  the  numerous  valves  which  permit  the 
lymph  to  flow  in  only  one  direction.  The  pressure  of  the 
lymph  in  the  spaces  about  the  lymph  capillaries  tends  to 
force  the  fluid  along  in  the  vessels,  and  the  pressing  of  a 
contracted  muscle  or  even  the  filling  of  the  lungs  with 
air  squeezes  the  lymph  vessels  and,  on  account  of  the 


THE   COUKSE   OF   THE   BLOOD 


127 


valves,  moves  the  contents  toward  the  veins.  One  of  the 
greatest  benefits  derived  from  exercise  is  the  freeing  of 
the  tissues  from  the  lymph  with  its  collected  impurities. 
Massage  produces  somewhat  the  same  effect  as  exercise. 

The  Course  of  the  Blood.  — The  movement  of  the  blood  is 
from  the  left  ventricle 
to  the  arteries  of  the 
body,  then  through  the 
capillaries  to  the  veins 
and  lymphatics  return- 
ing it  to  the  right 
auricle.  From  here  it 
goes  to  the  right  ven- 
tricle forcing  it  to  the 
pulmonary  artery  into 
the  lungs,  where  it 
passes  by  capillaries  to 
the  pulmonary  veins 
conveying  it  to  the 
left  auricle  opening 
into  the  left  ventricle. 
The  word  v-a-v-a-c  is 
an  aid  in  remembering 
that  the  blood  passes 
from  veins  to  auricles 
and  thence  to  ventricles  forcing  it  through  arteries  to 
capillaries. 

The  passage  of  the  blood  around  through  the  lungs  to 
the  left  auricle  is  called  the  pulmonary  circulation,  while 
its  flow  through  the  other  parts  of  the  body  is  known  as 
the  systemic  circulation.  A  part  of  the  systemic  circula- 


FIG.  89.  —  Lymph  vessels  of  the  head.  Note 
more  than  a  score  of  lymph  nodes  in  the 
neck.  (From  the  "  Reference  Handbook 
of  Medical  Sciences.") 


128 


THE  CIRCULATORY  SYSTEM 


tion  is  called  the  portal  circulation.  This  consists  of  the 
flow  of  blood  from  the  capillaries  and  veins  of  the  ab- 
dominal viscera  into  the  portal  vein  and  its  branches 
dividing  into  capillaries  within  the  liver. 

Rate  at  which  the  Blood  Flows. — The  rapidity  with 
which  the  blood  travels  has  been  determined  by  experi- 
ments    on    the    lower 


animals, 
through 
arteries 
fast     as 


It     passes 

the     largest 

ten    times    as 

through     the 


very  small  ones,  and 
flows  less  than  one  five- 
hundredth  as  fast  in 
the  capillaries  as  in  the 
aorta.  In  the  carotid 
artery  of  the  horse  it 
flows  one  foot  per 
second,  and  it  is  esti- 
mated that  it  requires 
one  second  to  pass 
through  the  entire 
length  of  a  capillary. 

Regulation   of  Blood 
Flow.  —  Since    more 

oxygen  is  required  during  exercise,  the  blood  must  flow 
more  rapidly  to  and  from  the  lungs  to  supply  the  demand. 
The  heart  is  made  to  beat  more  quickly  by  an  order 
sent  to  it  by  nerve  cells.  These  cells  have  been  stimu- 
lated by  the  oxygen-hungry  muscles  sending  a  notice 
of  their  wants. 


FIG.  90.  — Method  of  stopping  the  flow  of 
blood  from  a  cut  by  twisting  tight  a 
handkerchief  under  which  a  piece  of  wood 
has  been  thrust  over  the  brachial  artery. 


CIRCULATION    AND   HEALTH  129 

Hemorrhage,  or  Bleeding. —  A  blow  on  the  skin  often  in- 
jures the  small  blood  vessels,  so  that  ths  red  cells  escape 
or  the  vessels  become  distended  with  blood,  giving  the 
place  a  bluish  black  appearance.  If  the  skin  and  vessels 
are  broken,  the  blood  pours  out,  and  this  is  called  a  hemor- 
rhage. 

If  an  artery  is  cut,  the  blood  issues  in  spurts  corres- 
ponding to  the  heart  beats,  while  from  a  vein  the  flow  is 
steady.  Unless  the  vessel  is  large,  a  clot  will  soon  form 
and  check  the  flow.  The  hand  or  a  clean  cloth  held  over 
the  cut  helps  very  much  in  the  formation  of  a  clot.  The 
flow  from  an  artery  may  be  checked  by  pressing  tightly 
on  the  vessel  on  the  side  of  the  wound  toward  the  heart. 
A  handkerchief  or  cord  should  be  tied  loosely  around  the 
limb  between  the  cut  and  the  heart,  and  where  the  vessel 
lies  nearest  to  the  skin.  A  stick  or  folded  cloth  is  then 
to  be  slipped  under  the  ligature  and  over  the  vessel,  and 
the  ligature  then  tightened  by  twisting  it  with  a  stick. 
To  stop  the  bleeding  from  a  vein,  the  pressure  or  ligature 
should  be  applied  on  the  side  of  the  wound  away  from  the 
heart. 

A  quart  of  blood  may  be  lost  by  an  adult  without  dan- 
ger, and  twice  that  amount  may  escape  without  causing 
death. 

Circulation  and  Health. — Any  wearing  apparel  which 
hinders  the  free  circulation  of  the  blood  should  not  be 
used.  Garters  that  encircle  the  leg  and  tight  clothing 
about  the  waist  are  detrimental  to  health.  When  lymph 
collects  in  the  tissue  spaces  faster  than  it  is  removed,  a 
disease  known  as  dropsy  results.  Exercise  for  an  hour 
daily  is  necessary  to  promote  circulation  in  health. 

.  PHYS. 9 


130  THE   CIRCULATORY   SYSTEM 

Alcohol  and  the  Circulatory  System.  —  A  glass  of  beer 
or  a  glass  of  wine  has  a  perceptible  effect  on  the  circula- 
tion. The  arteries  of  the  skin  become  enlarged  and  the 
extra  blood  sent  to  the  surface  produces  the  redness  in 
the  face.  This  is  often  constantly  present  in  persons 
using  alcohol  daily.  Since  so  much  blood  is  near  the 
surface,  where  the  cold  air  may  carry  off  the  heat,  alcohol 
in  cold  weather  makes  the  body  colder.  A  drink  of 
whisky  in  winter  may  cause  a  man  to  feel  warm,  because 
much  blood  is  forced  into  the  skin,  where  the  sense  of 
heat  is  most  acute,  but  a  thermometer  shows  that  the  body 
throughout  becomes  colder.  The  experience  of  arctic 
travelers  proves  positively  that  those  using  alcohol  in 
severe  weather  are  the  ones  who  soonest  freeze  to  death. 

The  investigations  of  the  Committee  of  Fifty,  composed 
of  well-known  business  men  and  scientists,  show  that  in 
those  who  drink  large  quantities  of  beer  enlarged  hearts 
are  comparatively  frequent.  The  use  of  beer  is  a  promi- 
nent cause  of  fatty  degeneration  of  the  heart  muscle.  One 
in  every  sixteen  patients  in  the  hospitals  of  Munich  dies 
from  enlargement  of  the  heart,  due  to  the  drinking  of 
beer.  In  habitual  drunkards  the  coats  of  the  arteries  are 
liable  to  become  hardened,  so  that  a  little  extra  pressure 
will  produce  a  rupture.  The  breaking  of  a  vessel  in  the 
brain  often  results  in  apoplexy  or  paralysis. 

The  elements  in  the  blood  warding  off  all  kinds  of 
germ  diseases  are  weakened  in  those  using  much  alcoholic 
drinks,  so  the  chances  of  life  are  greatly  in  favor  of  total 
abstainers.  A  recent  publication  of  the  Committee  for 
the  Prevention  of  Tuberculosis  in  New  York  states: 
"  Alcoholism  is  admitted  by  all  authorities  to  be  an  im- 


SrGGESTICXSS   FOR   THE   TEACHER  131 

portant  factor  in  predisposing  to  tuberculosis.  Liquor  as 
a  beverage  is  never  useful  and  nearly  always  harmful. 
Alcoholism  must  be  considered  the  greatest  enemy  of  the 
welfare  of  a  nation,  the  most  frequent  destroyer  of  family 
happiness,  and  certainly  the  most  active  cooperator  of 
the  deadly  bacillus  tuberculosis." 

Questions 

1.  Point  out  the  location  of  the  heart  on  your  own  body.  2.  In 
what  way  do  the  cavities  of  the  heart  differ  ?  3.  Describe  the  pulmo- 
nary veins.  4.  Describe  the  valves  of  the  heart.  5.-  Explain  how  the 
heart  works.  6.  How  many  times  per  minute  does  your  pulse 
beat  after  running?  Wherein  do  the  arteries  differ  from  the  veins? 
7.  Name  four  arteries  and  tell  to  what  parts  th  ey  lead  the  blood.  8.  De- 
scribe the  capillaries.  9.  Name  the  largest  vein  and  largest  artery 
in  the  body.  10.  According  to  what  plan  are  the  arteries  and  veins 
named?  11.  Describe  the  largest  lymph  vessel.  12.  How  does  lymph 
of  the  finger  reach  the  blood  system  ?  13.  What  causes  the  flow  of 
lymph  ?  14.  Describe  the  course  of  the  blood  through  the  body. 
15.  At  what  rate  does  the  blood  flow  ?  16.  Explain  how  a  hemorrhage 
may  be  checked.  17.  In  what  way  does  exercise  benefit  circulation  ? 
18.  What  effect  has  alcohol  on  the  blood  vessels?  19.  How  does 
alcohol  affect  the  heart  ?  20.  State  the  influence  of  alcohol  on  the 
blood. 

Suggestions  for  the  Teacher 

1.  Ask  a  boy  to  secure  from  the  butcher  or  slaughterhouse  the 
heart  of  a  sheep,  pig,  or  calf.     Request  the  butcher  to  leave  in  place  an 
inch  or  two  of  all  vessels  attached  to  the  heart.     Arteries  may  be  dis- 
tinguished from  the  veins  by  their  thickness.     Note  the  soft,  small, 
and  thin-walled  auricles  at  the  top  of  the  heart  and  the  veins  entering 
them  from  the  back.     Cut  a  large  piece  out  of  the  front  side  of  each 
auricle  and  ventricle  to  show  the  valves.     Slit  open  the  pulmonary 
artery  at  its  junction  with  the  heart,  and  observe  the  three  semilunar 
valves.     This  specimen  may  be  preserved  in  the  formaldehyde  solu- 
tion. 

2.  Ask  a  pupil  to  show  how  to  stop  the  flow  of  blood  in  case  a  large 
artery  is  cut  in  the  wrist  or  a  vein  in  the  arm. 


XIII.   THE   RESPIRATORY  SYSTEM 

The  •  Use.  —  The  union  of  oxygen  with  any  substance 
produces  heat.  The  burning  of  wood  is  the  union  of  the 
oxygen  of  the  air  with  the  carbon  of  the  wood.  In  the 
same  way  the  body  is  kept  warm  by  the  union  of 
breathed-in  oxygen  with  the  food  or  tissues  in  the  system. 
Moreover,  energy  or  power  to  act  may  also  be  produced 
"by  the  union  of  oxygen  with  another  substance,  as  seen 
in  the  locomotive,  where  steam  is  formed  from  water 
heated  by  fire.  Fire  is  the  oxidation  of  the  fuel.  The 
oxygen,  uniting  with  the  dead  tissues,  burns  them  to  ashes, 
so  that  they  may  be  carried  out  of  the  body.  Depriving 
the  brain  of  oxygen  causes  fainting  or  unconsciousness. 

In  many  worms  and  salamanders  the  oxygen  needed 
passes  through  the  thin,  moist  skin  to  the  blood,  while  in 
all  insects  there  are  along  the  sides  of  the  body  several 
openings  from  which  tubes  branch  like  a  tree  among  the 
tissues  to  convey  oxygen.  Oysters,  fish,  and  many  other 
•creatures  dwelling  in  the  sea  have  gills  for  absorbing  the 
oxygen  contained  in  the  air  lying  between  the  particles  of 
the  water.  In  the  higher  animals  lungs  are  the  only  means 
of  procuring  oxygen  for  the  system.  The  respiratory  ap- 
paratus also  serves  to  get  clear  of  the  carbon  dioxide,  which 
is  a  part  of  the  ashes  resulting  from  oxidation.  Speech 
is  likewise  dependent  upon  the  organs  of  respiration. 

The  Parts.  —  The   respiratory  system  consists   of  the 
nasal  passages,  the  pharynx,  the  larynx,  the  trachea,  and 

132 


THE   PHAKYNX  133 

the  lungs.  The  nasal  passages  are  the  two  channels 
within  the  nose.  The  pharynx  is  the  irregular  cavity  at 
the  back  of  the  mouth.  The  larynx  is  the  cartilaginous 
box  at  the  top  of  the  trachea,  or  windpipe  conducting  air 
to  the  lungs  (Fig.  51). 

The  Nasal  Passages. — These  two  air  channels  of  the 
nose  are  separated  by  the  nasal  septum.  They  open  behind 
at  the  upper  and  back  part  of  the  mouth.  They  are  lined 
with  mucous  membrane,  in  which  are  glands  giving  out  a 
secretion  called  mucus.  This  is  sometimes  wateiy,  as  at 
the  beginning  of  a  cold,  or  thick  and  stringy,  as  when  one 
is  recovering.  The  mucus  is  of  great  service  in  preventing 
disease,  as  it  has  the  power  to  destroy  most  germs.  Thou- 
sands of  these  are  caught  daily  on  the  hairlike  processes, 
called  cilia,  sticking  out  from  the  surface  of  the  cells. 
The  numerous  hairs  in  the  passages  also  aid  in  holding 
back  the  germs  and  dust  from  entering  the  windpipe.  Be- 
cause of  these  facts  one  should  breathe  through  the 
nose  and  not  through  the  mouth,  which  has  no  special 
structures  for  restraining  the  dust  and  germs  from  the 
lungs. 

The  nasal  duct,  extending  from  the  inner  corner  of  the 
eye  obliquely  through  to  the  nasal  passages,  permits  the 
tears,  constantly  being  secreted,  to  escape  without  running 
down  the  cheek.  In  case  of  weeping,  the  duct  is  too  small 
to  convey  the  many  tears,  and  so  they  overflow.  The 
nerve  of  smell  is  distributed  to  special  cells  of  the  mucous 
membrane  in  the  upper  part  of  the  passages. 

The  Pharynx.  —  This  is  the  large  cavity  at  the  root  of 
the  tongue,  formed  by  the  union  of  the  nasal  passages 
and  the  mouth.  From  the  front  and  upper  part  of  the 


134 


THE   RESPIRATORY   SYSTEM 


pharynx  a  Eustachian  tube  leads  to  either  middle  ear. 
From  its  lower  part  open  the  esophagus  and  larynx.  On 
either  side  of  the  root  of  the  tongue  is  an .  oval  body 
nearly  an  inch  long,  called  the  tonsil  (Fig.  91).  Its  use 

is  not  known,  and 
it  is  often  removed 
by  the  doctor  when 
it  becomes  enlarged, 
as  is  the  case  in 
many  children. 

The  uvula  is  a 
small  finger-like 
body  hanging  down 
into  the  pharynx 
from  the  soft  palate 
which  forms  the  roof 
of  the  back  part  of 
the  mouth.  The 
hard  palate  is  the 
roof  of  the  mouth  in 
front  of  the  soft  pal- 
ate. Its  mucous 
membrane  lies 


FIG.  91. —The  tongue  and  opening  Into  the 
larynx,  seen  from  above,  a,  opening  from 
pharynx  to  esophagus;  &,  epiglottis  pushed 


forward  with  a  needle ;  c,  tonsil ;  e,  vocal  cords,     no.0:nQf  l^np    fFicy 
between  which  is  the  opening  to  the  larynx.          «g*U«    Done    <*lg. 


The  Larynx.  —  At  the  top  of  the  windpipe  is  a  tube 
about  two  inches  long  and  an  inch  wide,  made  of  two  large 
pieces  of  cartilage  and  several  small  ones.  The  pro- 
jecting part  of  the  large  cartilage,  the  thyroid,  forms 
Adam's  apple,  the  prominence  in  the  neck  under  the  chin. 
The  cartilages  are  united  by  membrane  and  muscle. 


THE   VOICE  135 

Within  the  larynx  is  a  Liver  of  mucous  membrane,  whose 
surface  cells  have  cilia  projecting  from  them  to  catch  and 
throw  upward  the  germs  and  dust. 

The  narrow,  slitlike  opening  from  the  pharynx  into  the 
larynx  is  the  glottis.  A  small,  somewhat  triangular  lid, 
the  epiglottis,  has  its  base  attached  just  in  front  of  the 
glottis.  A  projecting  fold  of  membrane,  passing  from 
before  backward  on  either  side  within  the  upper  part  of 
the  larynx,  forms  the  vocal  cords. 

The  Vocal  Cords.  —  These  are  two  ligarnentous  folds  of 
membrane,  the  ends  of  which  are  attached  to  the  cartilage 
of  the  larynx  (Fig.  91).  The  cords  may  be  rendered 
more  or  less  tense  by  certain  muscles  which  may  by  con- 
traction move  the  pieces  of  cartilage. 

The  stretching  of  the  cords  makes  the  passage  between 
them  small,  so  that  the  breathing  out  of  air  from  the 
lungs  causes  them  to  vibrate  and  produce  sounds  called 
voice.  When  sounds  are  so  modified  by  certain  positions 
of  the  tongue,  palate,  teeth,  and  lips  as  to  form  words 
speech  is  produced.  All  animals  from  frogs  to  man  have 
vocal  cords,  which  may  be  easily  seen  by  cutting  a 
larynx  of  a  calf  or  pig  lengthwise  from  before  back- 
ward. However,  no  animals  except  man  can  talk  because 
they  do  not  know  how  to  use  the  organs  of  the  mouth  and 
throat  in  the  right  way  to  form  the  proper  sounds. 

The  Voice.  — The  vocal  cords  are  longer  in  men  than  in 
women,  and  therefore  the  women  have  a  more  shrill  high 
voice.  The  longer  the  cords,  the  less  frequently  they 
vibrate  when  the  air  rushes  out  between  them.  The 
pitch  of  the  voice  depends  upon  the  number  of  vibrations 
per  second.  The  lowest  bass  note  is  produced  by  44 


136 


THE   RESPIRATORY   SYSTEM 


vibrations  per  second,  while  the  highest  note,  five  and  a 

half  octaves  above,  is  made  by  1980  vibrations  per  second. 
The  loudness  of  sound  depends  largely  upon  the  force 

with    which    the    air    is    expelled    through    the    larynx. 

In  whispering,  the    opening  between    the  vocal  cords  is 

so  wide  that  the  air  passes 
out  without  causing  any 
vibration,  and  the  current 
is  checked  at  intervals  and 
modified  by  the  lips,  tongue, 
and  teeth. 

The  quality  of  the  voice, 
which  differs  so  much  in 
singers  and  speakers,  de- 
pends not  only  on  the  con- 
dition of  the  vocal  cords,  but 
also  upon  the  shape  of  the 
mouth,  pharynx,  and  larynx, 
and  their  modification  by 
the  contraction  of  certain 
muscles.  The  nasal  twang 


FIG.  92.  —  Human    lungs,    h,   heart; 
i,  trachea. 

is  produced  when  the  nasal 

passages  are  partly  closed  by  a  cold  or  by  a  growth  of 
tissue  called  adenoids.  Hoarseness  is  due  to  a  swelling 
of  the  cords,  resulting  from  the  blood  and  lymph  collect- 
ing in  them  because  of  a  cold  or  too  long-continued  use. 

It  is  important  that  every  one  should  cultivate  a  smooth 
and  pleasant  tone  of  voice  and  avoid  making  harsh  and  rasp- 
ing sounds.  The  mouth  should  be  well  opened  in  speaking, 
the  soft  palate  elevated,  and  the  lips  moved  with  firmness. 

Some  years  ago   deaf  people  who  were  unable  to  talk 


THE  TRACHEA,   OB   WINDPIPE 


137 


except  by  making  characters  with  the  fingers  were  called 
deaf  and  dumb.  They  are  not  dumb,  but  their  deafness 
prevents  them  from  learning  to  speak  by  hearing.  They 
can  learn  to  talk,  however,  by  observing  how  another  holds 
the  lips,  tongue, 
and  teeth  when 
speaking. 

The  Trachea,  or 
Windpipe.  —  This  is 
a  tube  about  an  inch 
in  diameter  and 
four  inches  long, 
extending  from  the 
larynx  to  near  the 
center  of  the  chest, 
where  it  divides  into 
two  parts  called 
bronchi.  These 
branch  to  help  form 
the  lungs.  Since 
the  pressure  of  the 
muscles  and  the  air 
have  a  tendency  to 
push  together  the 
walls  of  the  trachea, 
they  are  stiffened  by 


Fia.  93.  —  Wax  cast  of  the  trachea  of  a  cat,  show- 
ing the  branches  of  the  trachea  in  the  lungs. 
The  trachea  was  poured  full  of  melted  wax, 
which  became  solid  when  cooled,  and  the  lung 
tissue  was  then  eaten  away  with  acid,  t, 
trachea;  6,  bronchus;  h,  bronchial  tube;  e, 
bronchioles.  Blood  vessels,  black,  t  Prepara- 
tion by  Sylvester,  of  Princeton  University.) 


more  than  a  dozen 

rings  of  cartilage,  incomplete  at  the  back.  Mucous  mem- 
brane forms  the  inner  layer  of  the  trachea,  and  cells  with 
cilia  cover  the  surface  and  aid  much  in  working  all  bac- 
teria and  dust  particles  up  to  the  mouth. 


138  THE   RESPIRATORY    SYSTEM 

The  Lungs.  — There  are  two  lungs,  the  left  one  being 
slightly  smaller  than  the  right.  Both  have  their  bases 
resting  on  the  diaphragm,  while  the  apex,  or  top,  of  each 
lies  just  back  of  the  collar  bone.  Between  them  is  the 
heart.  The  lungs  are  covered  by  a  transparent  membrane, 
the  pleura,  which  also  lines  the  thoracic  cavity.  Pleurisy, 
which  is  the  soreness  or  inflammation  of  the  pleura,  is 

caused  by  the  growth  of  germs  on 
the  membrane.  These  are  car- 
ried there  by  the  blood  or  lymph. 
The  lungs  are  spongy  bodies 
consisting  of  the  two  bronchi 
with  all  their  tubular  branches, 
enveloped  by  numerous  blood 

FIG.  94. -The  termination  of    veSsels,  nerves,  air  sacs,  and  con- 
one    of    the  thousands  of 

bronchioles,  br,  like  e  in    nective  tissue.     The   branches  of 
Figure  93.    al,  air  sac  with     each   bronchus    are    named    Iron- 

a  dozen  or  more  air  cells. 

chial  tubes.  The  smaller  termi- 
nal branches  beyond  the  bronchial  tubes  are  the  bron- 
chioles, each  of  which  ends  in  a  group  of  air  spaces, 
called  air  sacs.  The  walls  of  these  air  sacs  are  pushed 
out  in  a  dozen  or  more  places,  forming  tiny  pouches 
called  air  cells  (Fig.  94). 

The  Air  Cells.  —  In  the  lungs  are  millions  of  air  cells, 
all  of  which  form  part  of  the  walls  of  the  air  sacs  at  the 
termination  of  the  tubes  conveying  air.  By  air  cells 
is  meant  air  spaces  and  not  cells  such  as  are  spoken  of 
through  the  body.  The  walls  of  the  air  cells  are  as 
thin  as  tissue  paper  and  are  covered  with  a  network  of 
blood  capillaries.  The  oxygen  breathed  into  the  air 
cell  as  part  of  the  air  is  thus  able  to  reach  the  blood, 


HOW   BREATHING    IS    MAINTAINED 


139 


while  the  carbon  dioxide  passes  from  the  blood  to 
the  air  cell. 

The  air  in  the  air  cells  must  be  constantly  changed  to 
keep  up  the  supply  of  oxygen  and  to  get  rid  of  the  carbon 
dioxide.  This  is  done  by  the  action  of  many  muscles, 
producing  an  inward  and  then  an  outward  flow  of  air 
through  the  trachea 
and  tubes  of  the 
lungs.  This  pro- 
cess is  called  breath- 
ing and  is  necessary 
for  respiration. 

How  Breathing 
is  Maintained.  — 
Breathing  consists 
of  inspiration,  or 
inhaling  air  into 
the  lungs,  and  ex- 
piration,  or  exhal- 
ing air  out  of  the 
lungs.  The  air  or 
atmosphere  presses 

upon  every  object  it  touches  in  the  same  way  as  water 
presses  on  anything  immersed  in  it.  Air  flows  toward 
the  place  where  the  pressure  is  least.  The  pressure  of  air 
in  a  vessel  or  cavity  may  be  decreased  by  increasing  the 
size  of  the  vessel  or  cavity  and  not  permitting  any  air  to 
enter. 

When  the  lungs  are  removed  from  the  body  of  a  mouse 
and  placed  in  a  bottle,  with  a  glass  tube  extending  from 
the  trachea  out  through  a  hole  in  a  tight  rubber  cork,  and 


cffcr 


FIG.  95.  —  The  position  of  the  diaphragm  and 
ribs  when  the  chest  cavity  is  enlarged  to  admit 
air  into  the  lungs  is  shown  at  the  right.  The 
figure  on  the  left  shows  how  the  chest  cavity  is 
decreased  to  push  out  the  air  from  the  lungs. 


140  THE    RESPIRATORY   SYSTEM 

the  air  then  pumped  out  of  the  bottle,  the  lungs  will  ex- 
pand. The  air  runs  down  the  tube  and  presses  out  every 
air  sac,  thus  filling  the  space  that  the  air  had  occupied. 
During  life  air  goes  into  the  lungs  when  the  pressure  on 
the  outside  of  the  lungs  is  decreased  by  enlarging  the 
cavity  of  the  chest  (Fig.  95).  This  decrease  of  pressure 
is  produced  by  the  contraction  of  certain  muscles,  and 
when  these  muscles  are  relaxed,  the  pressure  of  the  ribs 
on  the  lungs  causes  the  breathing  out  of  the  air. 

How  Breathing  is  Regulated.  —  Breathing  occurs  usually 
at  the  rate  of  about  fifteen  times  per  minute.  During  sleep 
it  is  slower;  while  violent  exercise  increases  it  to  more 
than  thirty  times  per  minute.  This  is  due  to  the  fact  that 
in  sleep  the  tissues  are  more  quiet,  and  therefore  require 
little  oxygen,  while  during  exercise  the  muscles  are  con- 
suming oxygen  rapidly,  and  it  can  be  supplied  from  the 
lungs  only.  When  the  tissues  need  oxygen,  a  message 
is  sent  to  the  cells  of  the  spinal  cord,  which  orders  the 
muscles  of  the  chest  used  in  breathing  to  work  faster. 

Respiration.  —  Passing  air  in  and  out  of  the  lungs  is. 
wrongly  called  respiration.  True  respiration  is  of  two 
kinds :  the  external  or  blood  respiration  occurs  in  the 
lungs,  while  internal  or  tissue  respiration  takes  place  in  the 
tissues  all  over  the  body.  Blood  respiration  consists  in 
the  passage  of  oxygen  from  the  air  cells  into  the  blood 
and  of  the  carbon  dioxide  from  the  blood  into  the  air  cell. 
The  air  received  into  the  lungs  contains  in  every  10,000 
parts  4  parts  of  carbon  dioxide,  2096  parts  of  oxygen, 
and  7900  parts  of  nitrogen.  When  it  issues  from  the 
lungs,  there  are  438  parts  of  carbon  dioxide,  1602  parts  of 
oxygen,  and  7900  parts  of  nitrogen. 


THE  CAPACITY  OF  THE  LUNGS 


141 


Tissue  respiration  consists  in  the  giving  up  of  the 
oxygen  of  the  blood  to  the  cells  of  the  tissues,  and  the 
receiving  of  the  carbon 
dioxide  from  the  tissues 
into  the  blood.  No 
cell  can  do  its  work 
without  a  constant 
supply  of  oxygen,  and 
in  doing  its  work  some 
of  the  oxygen  must 
unite  with  the  carbon 
to  form  carbon  dioxide. 

The  Capacity  of  the 
Lungs.  —  In  ordinary 
breathing,  only  one  pint 
of  air  passes  in  and  out 
of  the  lungs.  This  is 
called  the  tidal  air.  In 
addition  to  this  three 
pints  of  air  'may  be 
breathed  in  by  effort.  This  is  complemental  air.  After 
the  ordinary  expiration  about  three  pints  of  air,  named 
the  supplemental  air,  may  by  effort  be  forced  out,  but 
there  will  still  remain  some  air  in  the  lungs.  This  is 
residual  air.  The  vital  capacity  of  the  lungs  is  the 
quantity  of  air  that  can  be  breathed  out  by  the  deepest 
expiration  after  the  deepest  inspiration.  The  usual 
amount  is  about  four  quarts  for  an  adult. 

Measuring  the  Lung  Capacity.  —  Some  idea  of  the  ca- 
pacity of  the  lungs  may  be  derived  by  measuring  the  cir- 
cumference of  the  chest  after  as  much  air  as  possible  is 


FIG.  96.  — Measuring  the  capacity  of  the 
lungs.  The  bottle  was  filled  with  water, 
which  is  being  forced  out  by  expiring 
the  air  from  the  lungs  through  the  rubber 
tube  slipped  up  into  the  mouth  of  the 
bottle  kept  under  water  in  the  pan. 


142 


THE   RESPIRATORY   SYSTEM 


forced  out,  and  then  again  measuring  it  after  the  fullest 
inspiration.  The  difference  is  usually  from  two  to  four 
inches.  More  accurate  knowledge  of  the  lung  capacity 
may  be  gained  by  filling  a  gallon  bottle  with  water,  cork- 
ing it,  turning  it  upside  down  in  a  pan  of  water,  pulling 
out  the  cork,  and  then  by  means  of  a  rubber  or  glass  tube 


FIG.  97. — On  the  left  is  shown  the  normal  position  of  the  organs  and  on 
the  right  the  effect  of  tight  clothing  worn  around  the  waist.  I,  liver; 
s,  stomach ;  i,  large  intestine. 

slipped  up  in  the  neck  of  the  bottle,  blowing  the  fullest 
expiration  of  air  into  it.  The  air  will  force  more  or  less 
of  the  water  out.  By  measuring  the  water  left  in  the 
bottle  and  subtracting  the  amount  from  one  gallon,  the 
vital  capacity  of  the  lungs  may  be  known. 

How  Clothing  affects  Breathing.  —  In  order  that  all 
parts  of  the  lungs  may  easily  be  filled  with  air,  both  the 
diaphragm  and  the  ribs  must  be  free  to  move.  Tight 
clothing  about  the  waist  not  only  hinders  free'  respira- 
tion, but  stops  in  some  degree  the  circulation  of  the 


SHORTNESS   OF    BREATH 


143 


blood,  and  worst  of  all  presses  the  internal  organs  of  the 
abdomen  out  of  place.  In  this  way  serious  ill  health  is 
often  caused  in  later  life.,  The  evil  results  of  tight  bands 
worn  about  the  waist,  especially  by  young  girls,  frequently 


FIG.  98. — Method  of  restoring  breathing  in  a  person  partially  drowned. 
This  individual  was  unconscious  about  a  quarter  of  an  hour  after  being 
taken  from  the  water.  (From  a  photograph  taken  after  recovery.) 


continues  to  make  the  life  of  the  victim  miserable  to  its 
end. 

Shortness  of  Breath.  —  The  least  exertion  sometimes 
causes  a  person  to  breathe  very  rapidly.  This  may  be 
due  to  heart  disease  or  may  result  from  tuberculosis 
having  destroyed  part  of  the  lung  tissue.  Excitement 
frequently  causes  the  nerves  to  send  a  message  to  the 
muscles  forming  part  of  the  walls  of  bronchioles,  and 


144  THE   RESPIRATORY   SYSTEM 

makes  them  contract  and  shut  off  much  of  the  air  from 
the  air  cells.  The  catching  for  breath  in  case  of  asthma 
is  due  to  the  contraction  of  the  muscles  of  the  air 
tubes. 

Modified  Breathing.  —  Sneezing  is  a  forced  expiration,  in 
which  most  of  the  air  is  made  to  pass  through  the  nose. 
Hiccoughing  is  a  sudden  inspiration,  caused  by  the  quick 
contraction  of  the  diaphragm.  Coughing  is  a  forced  ex- 
piration, in  which  the  larynx  is  suddenly  opened  wide. 
Snoring  is  an  inspiration  with  the  tongue  and  soft  palate 
held  in  such  a  position  as  to  make  the  air  pass  partly 
through  the  mouth  and  partly  through  the  nose  so  as 
to  produce  a  fluttering  of  the  soft  palate.  Whistling  is 
either  an  expiration  or  an  inspiration  with  the  lips  so 
puckered  as  to  cause  a  vibration  of  the  air  within  the 
mouth. 

Artificial  Breathing.  —  The  bite  of  a  poisonous  snake, 
electrical  shocks,  or  partial  drowning  may  cause  the  mus- 
cles controlling  breathing  to  cease  acting  for  a  few  min- 
utes. If  some  artificial  means  are  used  to  make  the  air 
pass  in  and  out  of  the  lungs  for  a  few  minutes,  the  ner- 
vous system  may  recover  from  the  shock,  and  normal 
breathing  again  take  place. 

Of  the  several  methods  in  use  to  produce  artificial 
breathing  that  brought  into  use  by  Schaefer,  in  1904, 
seems  to  be  the  most  effective.  The  patient  is  immedi- 
ately turned  face  downward,  and  a  heavy  folded  coat, 
plank,  or  bunch  of  weeds  is  laid  under  the  chest  arid 
upper  part  of  the  abdomen  (Fig.  98).  The  operator  then, 
standing  astride  and  facing  the  head  of  the  subject,  places 
his  hands,  one  on  either  side,  over  the  lowest  part  of  the 


EXERCISING   THE   LUNGS 


145 


ribs.  By  slowly  bending  forward  and  thus  pressing  on  the 
thorax,  the  air  is  driven  out,  and  by  gradually  relaxing  the 
pressure  without  moving  the  hands  from  their  places,  the 
air  is  drawn  into  the  lungs.  These  movements  should 
be  performed  about  a 
dozen  times  per  minute. 
A  half  hour  is  some- 
times required  to  estab- 
lish normal  breathing. 

Exercising  the  Lungs. 
—  The  lungs,  when 
filled  to  their  fullest 
extent,  contain  nearly 
five  quarts  of  air.  In 
ordinary  breathing 
only  about  a  half  quart 
of  air  passes  out  and 
in.  It  is  evident,  there- 
fore, that  many  of  the 
air  cells  are  not  being 
used  to  their  fullest  extent,  and  under  such  conditions 
disease  germs  are  more  likely  to  set  up  growth.  There 
is  much  evidence  to  show  that  consumption  may  be 
prevented,  and  in  many  cases  even  cured,  by  spending  a 
few  minutes  several  times  daily  in  filling  the  lungs  to 
their  fullest  capacity  at  every  breath,  and  by  living  in 
the  open  air  with  an  abundance  of  food. 

Breathing  exercises  also  cause  the  lymph  with  its  col- 
lected impurities  to  pass  on  into  the  blood  stream  for 
purification  by  the  kidneys  and  lungs.  These  exercises, 
practiced  daily  for  three  months,  will  often  enlarge  the 

DAV.  PHYS.  10 


FIG.  99.  —  Air  sacs  at  the  end  of  air  tubes  in 
the  lungs,  a,  from  a  lung  not  exercised ; 
b,  from  a  lung  well  exercised.  The  figures 
above  are  cross  sections  magnified. 


146 


THE   RESPIRATORY   SYSTEM 


chest  of  a  person  under  thirty  years  of  age  from  one  inch 
to  three  inches  in  circumference.  If,  when  the  lungs  are 
full  of  air,  the  chest  is  beat  lightly  with  the  fists,  the 
exercise  is  still  more  effective.  Round  and  drooping 

shoulders  and  weak  back 
muscles  are  corrected  in 
a  great  measure  by  lung 
exercises  together  with 
the  arm  movements 
upward  and  downward, 
outward  and  inward, 
and  forward  and  back- 
ward to  their  full  ex- 
tent. 

Some  Common  Dis- 
eases of  the  Respiratory 
System.  —  Nearly  all 
of  the  diseases  of  this 
system  are  due  to  germs. 

About  one  fourth  of  all  deaths  result  from  disease  of  the 
lungs.  Tuberculosis  kills  over  4,000,000  in  the  world 
annually,  and  pneumonia  destroys  about  as  many  in  the 
United  States  as  tuberculosis.  The  way  for  these  two 
diseases  is  often  prepared  by  catarrh,  an  inflammation  of  the 
mucous  membrane.  A  temporary  inflammation  of  the  lin- 
ing of  the  air  passages,  caused  by  germs  overcoming  the  body 
cells  when  weakened  by  exposure,  is  called  a  cold.  Mem- 
branous croup  and  diphtheria  are  diseases  of  the  throat,  pro- 
duced by  a  special  kind  of  bacteria  often  transferred  from 
mouth  to  mouth  by  the  drinking  cup.  Since  the  sputum 
coughed  up  from  the  throat  and  lungs  may  contain  some 


FIG.  100.  —  Expression  often  present  in 
children  with  adenoid  growths  in  the 
back  part  of  the  nose. 


TOBACCO   AND   THE    RESPIRATORY   SYSTEM 


147 


of  these  harmful  germs,  they  should  never  be  deposited  on 
the  sidewalk  or  on  the  floor  of  a  car  or  a  house.  When 
dried,  they  will  be  blown 
about  in  the  air,  breathed, 
and  thus  make  others  sick. 

Adenoids.  --  Adenoids 
are  spongy  growths  fre- 
quently occurring  in  the 
back  part  of  the  nasal 
cavities  of  children.  They 
interfere  with  the  blood 
supply  to  the  brain,  clog  up 
the  nasal  passages,  cause 
mouth-breathing  and  indis- 
tinct pronunciation  of 
words.  Listlessness,  inat- 
tention, poor  memory,  par- 
tial deafness,  and  frequent 
colds,  or  earache  may  re- 
sult from  adenoids.  These 
structures  are  very  common 
in  children  of  school  age. 
Signs  indicating  their  presence  are  parted  lips,  prominent 
eyeballs,  a  narrow  and  high-arched  roof  of  the  mouth,  and 
nasal  speech.  They  are  easily  removed  by  a  physician. 

Tobacco  and  the  Respiratory  System.  —  While  tobacco 
affects  more  seriously  the  heart  and  nervous  system,  yet  it 
also  leaves  its  evil  impress  on  the  respiratory  organs. 
The  heat  and  gases,  produced  in  smoking  tobacco,  tend 
to  dry  the  mucous  membrane  and  act  as  irritants  to  the 
throat,  nasal  passages,  and  larynx.  After  some  years 


FIG.  101.  — Section  of  the  head  show- 
ing adenoid  growths  a  and  6;  i, 
uvula ;  u,  tonsil ;  t,  tongue.  Arrows 
show  the  direction  of  the  air. 


148  THE   RESPIRATORY   SYSTEM 

those  addicted  to  the  chewing  of  tobacco  or  the  smoking 
of  the  cigarette  nearly  always  have  a  husky  voice,  due  to 
the  effects  of  tobacco  on  the  vocal  cords. 

In  cigarette  smokers  it  is  through  the  lungs  that  the 
poison  chiefly  readies  the  blood.  Those  using  pipes  and 
cigars  seldom  inhale  the  smoke  into  the  lungs,  while  over 
nine  tenths  of  the  cigarette  users  do.  This  permits  the 
carbon  monoxide,  a  poisonous  gas  generated  from  the  burn- 
ing of  the  tobacco,  and  the  nicotine  to  pass  readily  into 
the  blood  and  poison  the  nerves. 

An  examination  for  nine  years  of  the  boys  in  one  of  the 
large  eastern  colleges  showed  that  the  non-users  of  tobacco 
gained  during  four  years  in  chest  development  26.7  per 
cent  more  than  the  habitual  users  of  tobacco.  The  con- 
tinual use  of  tobacco  decreases  very  markedly  the  lung 
capacity,  as  has  been  shown  by  many  careful  measure- 
ments taken  at  a  New  England  college. 

Alcohol  and  the  Organs  of  Respiration.  —  One  of  the 
most  constant  effects  of  alcohol,  especially  if  used  in  con- 
siderable amounts,  is  to  lessen  the  rate  and  depth  of 
breathing.  In  this  way  many  of  the  air  cells  of  the  lungs 
fail  to  be  expanded,  and  disease  is  invited.  Of  all  the 
cases  of  tuberculosis  in  the  New  York  Hospital  on  Black- 
well's  Island,  one  half  are  declared  to  be  due  to  the  use  of 
alcohol.  Dr.  Crandall,  in  his  book  "  How  to  Keep  Well," 
states  that  users  of  alcohol  are  particularly  liable  to  pneu- 
monia. The  United  States  Census  Reports  show  that 
with  the  increased  use  of  alcoholic  drinks  in  this  country 
there  has  been  a  marked  increase  in  the  number  of  deaths 
resulting  from  pneumonia.  Physicians  declare  that  the 
use  of  alcoholic  drinks  causes  the  death  of  a  large  proper- 


SUGGESTIONS    FOB   THE   TEACHER  149 

tion  of  the  three  hundred  thousand  who  die  in  this  country 
yearly  from  disease  of  the  respiratory  organs. 

Questions 

1.  Of  what  use  is  oxygen  in  the  body  ?  2.  How  is  oxygen  supplied 
to  the  tissue  ?  3.  Name  the  parts  of  the  respiratory  system.  4.  Of 
what  special  use  are  the  nasal  passages  ?  5.  Describe  the  pharynx. 
6.  What  are  the  chief  features  of  the  larynx  ?  7.  Describe  the  vocal 
cords.  8.  How  is  voice  produced?  9.  On  what  do  the  loudness  and 
the  quality  of  the  voice  depend  ?  10.  Describe  the  trachea.  11.  Ex- 
plain how  the  air  tubes  end.  12.  Of  what  use  are  the  air  cells? 
13.  What  causes  the  air  to  rush  in  and  out  of  the  lungs  ?  14.  Why 
do  you  breathe  quicker  after  running?  15.  Explain  what  is  meant 
by  two  kinds  of  respiration.  16.  State  some  facts  concerning  the 
capacity  of  the  lungs.  17.  How  does  clothing  affect  breathing? 
18.  What  causes  shortness  of  breath?  19.  Describe  how  artificial 
breathing  may  be  produced.  20.  Why  is  it  important  to  exercise  the 
lungs?  21.  State  five  facts  concerning  disease  of  the  respiratory 
system.  22.  In  what  way  does  tobacco  harm  the  respiratory  system? 
23.  Give  some  evidence  showing  that  cigarettes  are  harmful.  24.  How 
does  alcohol  affect  the  respiratory  system?  25.  What  is  the  evi- 
dence that  alcohol  does  not  prevent  disease  ? 


Suggestions  for  the  Teacher 

1.  Procure  from  the  butcher  the  lungs  of  a  small  pig  or  lamb. 
Pick  loose  w7ith  a  pin  some  of  the  transparent  glistening  pleura  cover- 
ing the  surface  of  the  lungs.     Slit  open  the  trachea  and  bronchi,  not- 
ing the  mucous  membrane  lining  them,  and  observe  the  numerous 
branches  of  each  bronchus  as  it  pierces  deeper  into  the  lung. 

2.  The  larynx  of  a  calf  or  other  animal  secured  from  the  butcher 
will,  wrhen  cut  open  from  before  backward,  show  clearly  the  vocal  cords 
very  similar  to  those  in  man. 

3.  By  means  of  a  gallon  bottle  and  tube,  as  shown  on  page  141,  ask 
several  pupils  to  measure  the  capacity  of  their  lungs  and  also  the 
amqunt  of  air  ordinarily  expelled  at  a  breath.     This  will  tell  them 
how  much  of  the  lungs  is  unused,  and  therefore  in  a  condition  to  be- 
come diseased.     See  that  the  end  of  the  tube  put  into  the  mouth  is 


150  THE   RESPIRATORY   SYSTEM 

well  cleaned  after  each  pupil  uses  it.    A  glass  tube  is  preferable  to 
rubber. 

4.  Have  the  pupils  perform  the  following  lung  exercises  :  Standing 
erect,  with  shoulders  thrown  back,  breathe  in  through  the  nose  until 
the  lungs  are  entirely  filled ;  then  exhale.  Do  this  at  the  rate  of  a 
dozen  times  per  minute  for  five  minutes.  For  a  few  minutes,  at  the 
rate  of  thirty  times  per  minute,  swing  the  arms  up  and  down  from  the 
sides  of  the  body  to  above  the  head.  Then,  at  the  rate  of  forty  times 
per  minute,  extend  the  arms  forward  in  front  of  the  body  and  draw 
them  back  until  the  closed  fists  strike  the  chest.  During  the  next 
three  minutes  swing  the  extended  arms  forward  so  that  the  palms 
strike  together  in  front  of  the  body  and  then  backward  until  they 
strike  together  behind  the  back.  Explain  that  these  exercises,  prac- 
ticed daily  in  the  fresh  air,  are  of  great  importance  in  warding  off 
consumption  and  other  diseases. 


XIV.    AIR  AND   HEALTH 


Composition  of  Air.  —  Air  is  composed  chiefly  of  the 
two  gases  oxygen  and  nitrogen,  which  are  merely  mixed 
and  not  combined  chemically  like  carbon  and  oxygen 
in  carbon  dioxide.  Because  of  this  fact  the  blood  is 
able  to  take  up  the  oxygen  only,  without  in  any  way 
affecting  the  nitrogen.  The  fact  that  there  are  four  parts 
of  nitrogen  in  the 
air  to  one  part 
of  oxygen  may  be 
shown  by  causing 
the  oxygen  in  a  jar 
to  unite  with  the 
head  of  a  match. 
About  a  fourth  of 
a  match  bearing  the 
head  should  be  laid 


FIG.  102.  —  Experiment  showing  the  amount  of 
oxygen  in  the  air.  In  the  figure  at  the  left  c 
is  a  cork  bearing  a  piece  of  match,  which,  by 
burning,  used  up  the  oxygen  so  that  the  water 
rose  in  its  place,  as  shown  in  the  figure  at  the 
right. 


on  a  chip  of  wood  or  cork  floating  in  a  pan  of  water. 
After  lighting  the  wood  of  the  match  with  a  taper,  a 
glass  is  to  be  set  over  it  just  as  the  flame  reaches  the 
match  head.  The  oxygen  in  the  jar  will  be  used  up 
by  the  burning  sulphur  and  phosphorus,  and  no  more  can 
get  in  on  account  of  the  water  at  the  mouth  of  the  jar. 
The  white  fumes  formed  from  the  burned-up  oxygen  will 
be  absorbed  by  the  water,  which  will  then  rise  and  occupy 
the  same  space  before  filled  by  the  oxygen.  By  slipping 

151 


152  AIR   AND   HEALTH 

a  piece  of  paper  under  the  water  and  over  the  mouth  of 
the  glass,  it  may  be  turned  up  without  allowing  oxygen  to 
enter.  If  the  paper  cover  be  then  moved  to  one  side  a 
little  and  a  burning  stick  thrust  in,  the  flame  will  at  once 
go  out,  because  there  is  no  oxygen  present.  There  are 
about  4  parts  of  carbon  dioxide  in  every  10,000  parts  of 
air. 

The  Extent  of  the  Air.  —  The  air,  or  atmosphere,  ex- 
tends to  a  distance  of  ninety  miles  from  the  earth,  and  is 
present  in  the  soil  and  the  tissues  of  all  plants  and  ani- 
mals. Its  presence  in  water  makes  it  possible  for  fish  to 
get  oxygen  by  means  of  the  gills,  between  which  the  water 
is  continually  passing  from  the  mouth  outward  through 
the  opening  at  the  side  of  the  head.  At  high  elevations, 
as  on  mountain  tops,  the  air  is  much  less  dense,  and  it  is  on 
account  of  the  thinness  of  the  air  that  ascent  in  a  balloon 
above  five  miles  proves  fatal  to  the  occupants. 

The  Source  of  the  Air.  —  Billions  of  creatures  are  con- 
stantly using  the  oxygen  to  maintain  life,  and  a  new  sup- 
ply is  continually  being  formed  through  the  agency  of 
plant  life.  All  grass  and  trees  or  other  plants  of  a  green 
color  give  off  large  quantities  of  oxygen  under  the  influ- 
ence of  sunlight.  At  the  same  time  they  use  up  much 
carbon  dioxide  breathed  out  by  the  animals.  Plants  use 
oxygen  also  in  respiration,  but  they  get  during  daylight 
much  more  oxygen  than  they  can  use  from  the  carbon 
dioxide,  and  therefore  set  it  free.  Carbon  dioxide  and 
nitrogen  are  the  two  most  important  of  all  plant  foods. 

If  a  small  candle  is  lit  and  put  in  a  glass  box  having 
a  space  of  twelve  cubic  feet,  it  will  be  extinguished 
in  about  one  hour  by  the  carbon  dioxide  given  off.  If 


IMPURITIES   IN   THE    AIR  153 

the  same  experiment  is  made  again  and  the  box  is  filled 
with  large  leafy  plants,  and  exposed  to  the  bright  sun,  the 
candle  will  continue  to  burn,  because  the  carbon  dioxide 
is  consumed  by  the  plants. 

Gases  pass  to  and  from  the  plants  through  breathing 
pores,  which  appear  in  young  apple  and  pear  branches 
as  minute  white  elevations  smaller  than  the  head  of  a  pin. 
Breathing  pores  are  more  numerous  on  the  leaves,  but 
much  smaller,  so  they  can  be  seen  only  with  the  aid  of 
the  microscope  (Fig.  103). 

An   acre  of   grass  will  give  off    enough  oxygen  on   a 


FIG.  103.  —  Surface  of  a  leaf,  showing  eight  breathing  pores.    Photo- 
graphed through  the  microscope. 

bright  day  to  supply  the  wants  of  ten  people  at  ordinary 
labor.  The  fact  that  plants  do  yield  oxygen  may  be 
shown  by  placing  a  funnel  over  some  water  plants  in  the 
water  exposed  to  bright  sun,  and  running  the  tube  of  the 
funnel  into  a  small  vial  filled  with  water.  The  oxygen 
may  be  seen  rising  in  bubbles,  and  in  the  course  of  an  hour 
enough  of  it  will  have  collected  in  the  bottle  to  be  tested 
by  a  live  coal  on  a  burnt  stick.  If  oxygen  is  present,  the 
stick  will  burst  into  a  flame  when  thrust  into  the  bottle. 

Impurities  in  the  Air.  —  The   commonest   impurities  in 
the  air  out  of  doors  are  dust  and  germs,  some  of  which 


154  AIR   AND   HEALTH 

produce  disease.  Only  air  far  out  over  the  ocean  or  on 
the  top  of  high  mountains  is  quite  pure.  During  the 
first  hour  after  a  prolonged  rain  almost  no  impurities  are 
present  in  the  air  of  country  places.  The  number  of 
germs  in  city  air  during  business  hours  and  on  dry  days 
varies  usually  from  1000  to  10,000  in  every  cubic  yard. 
By  keeping  the  streets  well  sprinkled  these  numbers  may 
be  lessened  more  than  four  fifths.  Dust  and  particles 
of  soot,  together  with  many  germs,  tend  to  make  city  life 
much  less  healthy  than  life  in  the  country. 

Foul  Air.  —  This  is  air  so  full  of  gases  from  decaying 
matter  or  other  sources  that  it  has  a  bad  odor  and  cannot 
be  breathed  long  without  affecting  the  health.  The  air 
of  a  room  containing  many  people  for  an  hour  without 
ventilation  becomes  foul.  In  mines  or  deep  wells  carbon 
dioxide  sometimes  collects  and  causes  quick  death  by 
suffocation  to  any  one  descending  into  them.  It  does 
this  by  preventing  the  red  cells  of  the  blood  from  get- 
ting enough  oxygen  to  carry  to  the  tissue.  Foul  air, 
such  as  that  from  sewers  or  cesspools,  generally  contains 
no  germs,  and  therefore  cannot  convey  to  a  person  such 
diseases  as  diphtheria  and  typhoid  fever,  as  some  people 
suppose. 

Night  Air.  —  Until  late  years  night  air  was  considered 
unhealthy,  because  those  who  were  out  after  night,  espe- 
cially in  wet  regions,  were  often  attacked  a  few  days  later 
with  malaria.  It  is  now  known  that  the  malaria  was  not 
due  to  night  air,  but  to  minute  animal  germs  trans- 
ferred from  one  person  to  another  by  the  bite  of  a  certain 
kind  of  mosquito,  in  which  the  malaria  germs  live  and 
multiply  after  the  insect  has  sucked  blood  from  a  malaria 


MOUNTAIN    AIR 


155 


patient.  One  may  sleep  in  the  swamps  and  morasses 
in  any  part  of  the  world  without  taking  malaria  if  the 
mosquitoes  are  kept  away  by  netting. 

No  one  can  get  too  much  night  air  if  he  keeps  warm. 
Night  air  has  by  analysis  been  shown  to  be  much  purer 
than  day  air,  because  the  dust  and  germs  settle  to  the 
earth  when  no  one  is 
about  to  stir  them  up. 
At  night  the  windows 
of  the  bedroom  should 
be  kept  open  if  one 
wishes  to  avoid  colds, 
pneumonia,  and  espe- 
cially consumption. 
During  cool  weather  it 
is  important  that  the 
head  should  be  pro- 
tected by  a  nightcap 
if  there  is  any  tendency 
to  catarrh  or  sore  throat. 
Sleeping  in  the  night  air  has  been  one  of  the  most 
efficient  means  used  in  curing  thousands  of  cases  of 
tuberculosis. 

Mountain  Air.  —  Some  people  feel  better  when  living 
in  a  mountainous  region,  and  frequently  those  affected 
with  lung  disease  are  sent  to  the  mountains  to  recuperate. 
The  beneficial  effect  of  mountain  air  may  be  due  in  part 
to  the  fact  that  it  contains  less  germs  and  dust  and  is 
drier,  but  the  chief  benefit  comes  from  the  fact  that  the 
air  is  not  so  dense  and  the  patient  must  exercise  his  lungs 
more  to  get  the  necessary  amount  of  oxygen  to  feed  the 


FIG.  104.  —  Two  malaria  germs  each  in  a 
blood  corpuscle.  Photographed  through 
the  microscope. 


L56  AIR   AND    HEALTH 

tissues.  It  has  been  found  that  lung  disease  can  be  cured 
almost  as  well  in  any  pure  air  if  the  patient  will  follow 
the  physician's  rules  in  reference  to  hygiene. 

Seashore  Air.  —  There  is  undoubtedly  some  element  in 
the  air  along  the  sea  not  to  be  found  inland.  Certain 
forms  of  tuberculosis,  especially  that  affecting  the  bones, 
get  well  in  seashore  air  sooner  than  elsewhere.  The  sea- 
shore is  also  beneficial  to  sufferers  from  hay  fever. 

Respired  Air.  —  This  is  air  which  has  been  acted  on  by 
the  blood  in  the  capillaries  of  the  lungs  and  then  expelled. 
It  consists  of  about  80  parts  nitrogen,  16  parts  oxygen, 
and  4  parts  carbon  dioxide.  This  shows  that  the  blood 
has  taken  up  4  parts  of  oxygen  and  given  out  in  return  4 
parts  of  carbon  dioxide,  while  the  nitrogen  is  in  no  way 
affected.  Although  germs  are  always  present  in  the  in- 
spired air,  no  germs  are  given  out  in  the  expired  air,  even 
if  the  person  is  suffering  from  some  disease.  The  germs 
are  held  fast  on  the  moist  mucous  membrane.  A  sudden 
expiration,  such  as  a  cough  or  a  sneeze,  will,  however,  throw 
out  many  germs.  As  the  expired  air  contains  much  more 
moisture  and  heat  than  that  inspired,  this  is  one  way  in 
which  the  body  loses  heat  and  water.  A  minute  amount 
of  organic  matter  is  also  present  in  respired  air,  and  it  is 
partly  this  which  makes  the  air  of  unventilated  rooms  so 
unhealthy. 

Need  of  Ventilation.  —  No  one  is  expected  to  eat  the 
food  which  has  been  once  in  his  stomach  or  that  of  an- 
other and  then  cast  out.  Neither  should  one  be  expected 
to  take  into  his  lungs  the  air  which  has  just  come  from 
them  or  from  the  lungs  of  some  one  else.  This  uncleanly 
habit,  however,  is  common  in  most  churches,  schools,  and 


HOW   TO   VENTILATE  157 

other  public  indoor  gatherings.  Ventilation,  which  means 
allowing  the  free  entrance  of  pure  air  and  the  passing 
out  of  the  impure  air,  is  poorly  provided  for  in  most  school- 
houses.  As  a  result  the  children  become  listless  and  in- 
attentive, and  the  teacher  frets  and  scolds  because  of  a 
weariness  of  the  flesh  produced  not  by  work  but  by  bad 
air.  Boys  and  girls  at  school  do  not  break  down  from 
overstudy,  but  from  lack  of  exercise  and  fresh  air.  Liv- 
ing in  closed  rooms  by 
day  and  sleeping  with- 
out windows  raised  at 
night  is  a  gentle  way  of 
committing  suicide. 

How  to  Ventilate.  - 
Since  the  flow  of  cold 
air  upon  the  body  may 

make    one   ill,  the   fresh     FIG.  105.  —  Experiment  in   ventilation.     A 

air    must    have    inlets      £•*•>•-*—«»"*<»*•"•«"'» 

where  it  will  not  strike 

directly  on  any  one  in  the  room.  Two  or  three  windows 
all  on  one  side  of  the  room,  pulled  down  several  inches 
from  the  top  and  raised  a  few  inches  at  the  bottom,  afford 
excellent  ventilation.  If  a  board,  slanting  inward,  is 
placed  in  the  bottom  of  the  window  so  as  to  direct 
the  current  of  air  upward,  no  draft  will  usually  be 
felt,  even  by  those  within  a  few  feet  of  the  window. 
The  height  of  the  board  should  be  twice  as  great  as 
the  opening  in  the  window,  and  triangular  pieces  at  the 
ends  will  shut  out  the  current  tending  to  enter  there. 

To  show  clearly  how  to  ventilate,  a  box  with  a  small 
lighted  candle,  as  in  Figure  105,  may  be  used.     The  candle 


158 


AIR   AND   HEALTH 


uses  up  oxygen,  makes  heat,  and  gives  off  carbon  dioxide 
in  the  same  way  that  people  do.  Four  half-inch  holes, 
bored  in  each  end  of  a  box  with  a  capacity  of  400  cubic 

^ inches,  are  fitted  with  corks 

and  a  pane  of  glass  serves 
for  one  side.  By  removing 
the  corks  from  one  group 
of  holes  at  a  time,  it  is 
easy  to  determine  which 
supplies  the  larger  amount 
of  air,  as  the  candle  flame 
goes  up  and  down  accord- 
ing to  the  amount  of  oxy- 
gen and  carbon  dioxide 
present.  With  all  the 
corks  in,  the  candle  is  ex- 


tinguished in  one  minute. 
If  two  corks  on  the  same 
end  at  the  top  are  removed, 
the  candle  will  burn  two 
minutes.  The  removal  of 
Fia.  106.— Diagram  showing  how  to  the  two  corks  at  the  top  in 


both  en(Js  allows  the  candle 
to  bum  three  minutes, 
while  if  the  Corks  are  all 


open  the  windows  so  that  all  pupils 

may  have  fresh  air.    The  course  of 

the  air  currents  were  determined  by 

smoke    and  the   brightness  of   the 

candles  burning  in  different  parts  of 

the  box.    i,  inlet  for  air;   o,  outlet     ID-  except   two   in   the   Same 

for  foul  air.    The  dotted  line  is  the     en(J    one   being    out   at  the 

level  of  the  heads  of  the  pupils. 

top  and   the    other  at   the 

bottom,  the  candle  will  continue  to  burn  until  con- 
sumed. This  is  clear  proof  that  only  two  openings, 
one  low  and  one  high,  on  the  same  side  of  a  room  afford 


HOW   TO    VENTILATE 


159 


better  ventilation  than   twice  as   many  opening   at   the 
top. 

When  a  basement  heater  is  used,  plenty  of  fresh  air 
may  be  furnished  by  leading  it  through  a  duct  from  the 
outside  to  the  furnace  to  be  heated  and  sent  to  the  rooms 
above.  On  thrs 
account  hot  air  is 
much  more  healthy 
than  steam  for  heat- 
ing purposes  unless 
a  special  arrange- 
ment is  made  for 
supplying  fresh  air 
or  drawing  the  im- 
pure air  out  by 
means  of  a  fan. 
When  air  is  forced 
into  a  room,  it 
should  enter  near 


FIG.  107.  — Section  of  a  schoolroom  heated  by  a 
stove.  Arrows  show  the  course  of  air  currents. 
a,  fresh  air  duct ;  6,  stove ;  c,  sheet  iron  jacket ; 
d,  outlet  for  impure  air;  e,  smokepipe;  /,  flue 
for  impure  air. 


the  ceiling,  and  an 

opening    for    the 

escape    of   the   impure   air  should  be  on  the  same   side 

of  the  room  near  the  floor. 

The  thousands  of  schoolrooms  in  rural  districts  where 
the  stove  is  used  may  be  well  ventilated  by  adopting  the 
plans  shown  in  the  figure.  The  stove  is  surrounded  by  a 
sheet-iron  jacket  standing  off  about  six  inches.  The  pure 
cold  air  enters  through  the  duct  beneath  the  stove,  which 
warms  it  as  it  flows  upward  and  then  over  the  room,  as 
shown  by  the  arrows.  Behind  the  stove  is  an  opening 
into  a  brick  flue  for  the  escape  of  the  impure  air.  This 


160  AIR   AND   HEALTH 

flue  extends  above  the  roof  and  contains  the  sheet-iron 
smoke  pipe,  which  warms  the  air  and  thus  makes  an  up- 
ward draft.  Good  ventilation,  with  a  pan  of  water  on  the 
stove  to  keep  the  air  moist,  will  prevent  much  of  the 
catarrh  and  colds  from  which  children  suffer. 

One  certain  means  of  getting  a  supply  of  fresh  air  in 
a  schoolroom  is  to  have  a  few  minutes'  recess  at  the  end 
of  each  hour  and  open  wide  the  doors  and  windows. 
Prevention  of  ill  health  is  better  than  curing  it.  Late 
investigations  prove  that  fresh  air  is  one  of  the  three 
greatest  preventives  of  disease. 

Amount  of  Air  Breathed.  —  At  each  breath  an  adult  uses 
about  30  cubic  inches  of  air,  and  as  breathing  occurs 
nearly  20  times  per  minute,  600  cubic  inches  of  air  are 
inhaled,  making  a  total  of  36,000  cubic  inches  per  hour. 
The  air  of  the  schoolroom  should  never  contain  more 
than  7  parts  of  carbon  dioxide  in  10,000.  To  prevent 
the  air  from  becoming  impure,  2000  cubic  feet  of  fresh  air 
should  be  supplied  every  hour  for  each  pupil. 

Temperature  and  Moisture.  —  One  cannot  think  well  or 
work  to  his  greatest  capacity  in  a  room  that  is  too  warm. 
If  the  room  is  too  cold,  illness  may  result.  The  most 
favorable  temperature  for  a  schoolroom  is  sixty-eight  de- 
grees. Overheated  rooms  cause  many  children  to  take 
cold  in  winter.  Frequently  the  air  of  a  room,  on  account 
of  the  heat,  is  so  much  drier  than  the  atmosphere  that  it 
gives  rise  to  a  catarrh  or  inflammation  of  the  mucous 
membrane  of  the  nose  and  throat.  The  air  may  be  kept 
moist  by  a  pan  of  water  set  on  the  stove  or  radiator. 

Sweeping  and  Dusting.  —  Rugs  are  preferable  to  nailed- 
down  carpets,  for  they  may  be  put  out  of  doors  in  the  sun 


DISEASE  AND   AIR  161 

for  cleaning.  The  dust  may  be  then  beaten  out  of  them 
without  settling  in  the  room.  Floors  and  furniture  should 
be  wiped  with  a  damp  cloth  to  which  the  dust  and  germs 
will  adhere  and  not  fly  into  the  mouth  of  the  cleaner. 
There  is  evidence  to  show  that  disease  germs  are  present 
on  the  floors  of  all  public  buildings  and  of  most  houses  in 
towns  and  cities.  Care  in  cleaning  means  escape  from 
sickness. 

A  short  time  ago  the  Upsala  Street  School  of  Worcester, 
Massachusetts,  decided  to  throw  away  the  old  feather 
dusters  and  use  moist  cloths  for  dusting :  as  a  result  there 
was  not  a  case  of  contagious  disease  in  a  school  of  425 
pupils  during  the  entire  school  year.  This  condition  of 
health  had  never  prevailed  before  in  the  history  of  the 
school. 

Disease  and  Air.  —  Dust-laden  air  and  air  in  poorly  ven- 
tilated rooms  is  known  to  be  responsible  for  much  of  the 
illness  affecting  the  respiratory  system.  Tool  grinders, 
cement  workers,  and  factory  hands,  breathing  air  laden 
with  minute  particles  of  matter  cast  off  from  the  ma- 
terials upon  which  they  are  working,  are  specially  liable 
to  lung  diseases.  All  patients  at  sanatoria  for  consump- 
tion are  compelled  to  remain  practically  out  of  doors  night 
and  day.  Even  with  the  thermometer  twenty  degrees 
below  zero,  one  entire  side  of  the  room  in  which  the 
patient  sleeps  is  left  open.  More  than  half  of  those  tak- 
ing this  fresh  air,  rest,  and  food  treatment  at  the  sanato- 
ria in  this  country  recover  from  their  sickness.  If  fresh 
air  will  cure  disease,  it  surely  will  prevent  disease. 


DAT.  PHY8.  — 11 


162  AIR   AND   HEALTH 

Questions 

1.  What  is  the  composition  of  air  ?  2.  How  can  you  separate  the 
nitrogen  from  the  oxygen  of  the  air  ?  3.  What  is  the  source  of  the 
oxygen  of  the  air  ?  i.  How  can  you  show  that  plants  give  off  oxygen  ? 
5.  Name  some  of  the  impurities  in  air.  6.  Describe  foul  air  and  its 
effect  on  health.  7.  Why  should  persons  sleep  with  their  windows 
open  ?  8.  Explain  fully  how  to  ventilate  a  room  in  summer.  9.  Ex- 
plain how  to  ventilate  a  schoolroom  heated  with  a  stove.  10.  How 
much  pure  air  is  required  for  each  person  per  hour?  11.  How  do 
temperature  and  moisture  affect  health?  12.  How  may  the  air  of 
a  room  be  kept  moist  ?  13.  Why  should  nailed-down  carpets  not  be 
used  ?  14.  What  is  the  effect  of  breathing  much  dust  ? 


Suggestions  for  the  Teacher 

1.  Prepare  a  cup  of  limewater  by  pouring  slowly  a  half  glass  of 
warm  water  on  a  heaping  tablespoonful  of  fresh  lime.     Five  minutes 
later  add  to  this  a  glass  of  water,  stir  well  and  pour  it  into  a  bottle 
which  should  be  well  corked.     The  clear  liquid  appearing  in  a  day  or 
two  on  top  of  the  sediment  is  limewater.     Put  some  of  this  into  a  cup, 
and  with  a  glass  tube  let  a  child  breathe  a  few  times  into  the  liquid. 
The  white  material  resulting  is  calcium  carbonate,  formed  by  the  union 
of  the  carbon  dioxide  of  the  breath  with  the  lime.     Place  a  dish  of 
limewater  and  a  lighted  candle  in  a  box  for  a  few  minutes,  and  note 
the  result.     Let  some  dishes  of  limewater  stand  an  hour  or  two  in 
rooms  that  are  well  ventilated  and  some  dishes  in  other  rooms  not 
well  ventilated,  and  note  the  result. 

2.  Ask  some  of  the  pupils  to  make  a  box  for  ventilating  experi- 
ments, as  shown  on  page  157.     Show  how  poorly  the  candles  burn 
when  there  is  poor  ventilation,  and  explain  that  the  human  body  is 
weakened  in  the  same  way  by  an  insufficient  supply  of  pure  air. 

2.  Demonstrate  upon  a  pupil  the  method  of  producing  artificial 
breathing  and  then  require  some  of  the  pupils  to  continue  the 
demonstration, 


XV.   ALCOHOLIC  DRINKS  AND  THEIR 
EFFECT   ON   THE   HUMAN    RACE 


How  Alcohol  is  Made. — There  are  many  different  kinds 
of  alcohol,  each  of  which  is  produced  in  a  different  way. 
Wood  alcohol  is  made  by  roasting  wood  and  catching  the 
vapors  that  pass  off.  The  alcohol  used  in  drinks  is  al- 
ways produced  by  the  growth  of  yeast  in  a  liquid  con- 
taining sugar.  The  yeast  is 
an  oval  or  spherical  one- 
celled  plant  too  small  to  be 
seen  except  under  a  micro- 
scope magnifying  a  hundred 
diameters. 

A  yeast  cake,  such  as 
is  purchased  at  the  store, 
contains  millions  of  yeast 
plants.  They  multiply  by 
budding.  That  is,  a  little  FlG  108 
projection  pushes  out  on 
one  side  and  continues  to 
grow  a  half  hour  until  it  is  the  size  of  the  mother  plant. 
If  a  yeast  cake  is  put  in  a  glass  of  water  in  which 
a  heaping  teaspoonful  of  sugar  has  been  dissolved,  the 
yeast  will  grow  rapidly  when  kept  in  a  warm  place.  The 
chemical  action  produced  by  the  growth  is  fermentation. 
In  an  hour  or  two  the  appearance  of  bubbles  shows  that 

163 


Yeast  plants,  many  of 
which  bear  buds.  Photographed 
through  the  microscope. 


164 


ALCOHOLIC    DRINKS 


the  growing  yeast  is  separating  the  sugar  into  alcohol 
and  carbon  dioxide.  This  process  is  called  fermentation. 
After  it  continues  about  six  hours,  the  liquid  will  have  a 
biting  or  sour  taste,  due  to  the  alcohol  formed. 

Distillation. — In  a  sugar  solution  yeast  will  stop  grow- 
ing when  the  amount  of  alcohol  formed  is  about  one 

seventh  part  of  the 
solution.  This  is 
due  to  the  fact  that 
alcohol  tends  to  de- 
stroy life.  In  order 
to  get  a  stronger 
solution  of  alcohol, 
such  as  whisky,  this 
weak  solution  must 
be  heated  to  near 
the  boiling  point 
in  a  vessel  with  a 
cork,  through  which 
passes  a  bent  tube 

to  another  vessel  surrounded  by  cold  water.  Heat  causes 
the  alcohol  to  pass  over  in  the  form  of  vapor  into  the 
vessel  set  in  cold  water.  Here  the  cold  changes  the 
steam,  or  vapor,  back  to  a  liquid,  which  is  a  strong  solu- 
tion of  alcohol.  This  process  is  known  as  distillation, 
and  the  alcoholic  drinks  so  produced  are  called  distilled 
liquors,  or  spirits. 

Whisky  is  usually  made  in  this  country  from  rye  or 
corn.  The  grains  are  sprouted  in  a  moist  warm  room  to 
change  their  starch  into  sugar.  This  product,  when  dried, 
is  called  malt.  By  mixing  the  malt  with  water  and  add- 


FIG.  109.— A  simple  distilling  apparatus,  i,  inlet 
for  cold  water;  o,  outlet  for  cold  water;  w, 
outlet  for  alcohol. 


AMOUNT  OF   ALCOHOLIC   DRINK  CONSUMED          165 

ing  yeast  plants,  alcohol  is  later  produced.  Brandy  is  a 
distilled  liquor  made  from  grape  juice  in  which  yeast  has 
formed  alcohol.  Rum  and  gin  are  also  distilled  liquors. 

Fermented  liquors  include  all  kinds  of  wine.  They  con- 
tain much  less  alcohol  than  the  distilled  drinks.  They 
are  produced  by  the  growth  of  yeast  in  the  juices  of  fruits, 
such  as  grapes  and  berries.  Malt  liquors,  such  as  beer, 
porter,  and  stout,  contain  only  a  small  amount  of  alcohol. 

They  are  so  named  because  of  the  malt,  or  sprouted 
grain,  used  to  secure  the  sugar  for  the  yeast  plant  to  feed 
on.  In  fermented  liquors  the  sugar  from  which  the 
alcohol  is  formed  is  present  in  the  fruit  juice. 

Amount  of  Alcohol  in  Liquors.  —  The  strong  alcoholic 
drinks  composed  of  about  one  half  pure  alcohol  are 
whisky,  brandy,  rum,  and  absinthe.  The  drinks  of  me- 
dium strength,  containing  from  fifteen  per  cent  to  thirty 
per  cent  of  alcohol,  include  many  of  the  liquid  patent 
medicines,  gin,  port  wine,  and  sherry.  The  weak  bever- 
ages, containing  from  three  per  cent  to  twelve  per  cent  of 
alcohol,  are  beer,  stout,  porter,  ale,  champagne,  cider,  and 
many  common  red  wines.  Most  of  the  beer  made  in  this 
country  contains  about  five  per  cent  of  alcohol,  the  ordi- 
nary wines  have  about  ten  per  cent,  and  the  best  whisky 
contains  fifty-five  per  cent.  Apple  cider,  after  standing 
three  days  in  summer,  may  have  as  mu3h  as  six  per  cent 
of  alcohol. 

Amount  of  Alcoholic  Drink  Consumed.  —  There  are  twenty- 
five  times  as  much  beer  as  wine  consumed  in  the  United 
States,  and  nearly  twice  as  much  whisky  as  wine.  The 
quantity  of  beer  used  yearly  by  our  people  is  over 
1,000,000,000  gallons.  So  intemperate  and  beastlike  does 


166 


ALCOHOLIC    DRINKS 


alcohol  sometimes  render  people  that  they  frequently 
have  no  control  over  their  appetites  after  taking  a  few 
drinks. 

About  $75,000,000  worth  of  patent  medicines  contain- 
ing alcohol  is  sold  yearly.  Dr.  A.  P.  Grinnell,  who 
has  made  a  study  of  this  subject,  declares  that,  with  the 
exception  of  ale  and  beer,  more  alcohol  is  consumed  in 
patent  medicines  than  is  dispensed  by  the  licensed  saloon. 

The  value  of  all  kinds 
of  liquors  produced 
annually  is  about  a  half 
billion  dollars.  To  pro- 
duce them  60,000,000 
bushels  of  grain  are 
used. 

Use  of  Alcoholic  Drink 
Decreasing.  — Owing  to 
the  education  of  the 
public  concerning  the 
consumption  of  strong 
In  1840,  when 


1872 

/S82 

1832 

13O2 

FIG.  110.  —  The  sizes  of  the  rectangles  show 
how  the  use  of  alcohol  has  decreased 
each  decade  in  seven  of  the  large  London 
hospitals  while  the  number  of  patients 
has  greatly  increased. 


evils  of  the  drink  habit,  the 
alcoholic  liquors  has  decreased  greatly, 
nearly  every  family  used  some  whisky,  the  average 
amount  consumed  for  each  inhabitant  was  two  and  a  half 
gallons,  while  in  1896  the  amount  was  only  one  gallon 
for  each  individual.  A  half  century  or  more  ago  the 
labor  organizations  set  aside  money  to  buy  liquor  at  their 
meetings.  To-day  many  of  the  unions,  such  as  the  Metal 
Polishers,  Core  Makers,  Iron  Molders,  and  Knights  of 
Labor,  exclude  any  one  engaged  in  the  liquor  traffic. 

Recent    investigations    of    the    rules   of    many   large 
business     corporations     brought     forth     the     fact     that 


ALCOHOL    IX    HEALTH 


167 


1794    of    them    prohibit    the    use    of    alcoholic     drink 
by   their   employees.     Hundreds   of   towns,  many   coun- 
ties,   and    a    few    states    have    voted    to    prohibit    the 
manufacture  and  sale  of   alco- 
holic drinks  within  their  bound- 
aries.    It  is  unfortunate,  how- 
ever, that  the  quantity  of  beer 
consumed  annually  has  greatly 
increased.     This  may  be  due  in 
part  to  the  fact  that  the  people 
are  not  yet  aware  of  the  power 
of  beer  as  a  destroyer  of  health, 
home,  and  happiness. 

Alcohol  in  Health. -- While 
it  is  possible  for  some  older 
persons  to  drink  small  amounts 
of  liquor  daily  for  many  years 
without  apparent  injury  to  them- 
selves, yet  experience  shows 
that  of  those  beginning  the  use 
of  beer,  wine,  or  whisky  before 
the  age  of  twenty-five  a  large 
percentage  are  injured  in  health 
by  the  alcohol.  The  recent  re- 
port of  the  Committee  of  Fifty, 
known  far  and  wide  for  its 
thoroughness  and  accuracy, 

furnishes  evidence  that  about  1,000,000  men  are  every 
year  drinking  to  such  an  excess  as  to  cause  evident 
injury  to  health. 

The  excuse  often  given  for  the  use  of  these  beverages 


FIG.  111.  —  Diagram  showing- 
how  a  small  amount  of  alcohol 
taken  on  alternate  days  af- 
fected a  type  setter.  The  fig- 
ures at  the  left  show  the  num- 
ber of  letters  set  up. 


168  ALCOHOLIC   DRINKS 

is  that  they  help  one  to  perform  more  work.  The  Com- 
mittee of  Fifty  declares  that  the  use  of  alcoholic  drinks 
just  before  or  during  physical  or  mental  work  usually 
diminishes  the  total  amount  of  work  done.  Dr.  Wood- 
head,  a  professor  in  Cambridge  University,  writes  as  fol- 
lows: "No  amount  of  alcohol,  however  given,  can  increase 
the  amount  of  work  done  in  that  same  period  without 
giving  rise  to  very  serious  disturbances  in  some  part  or 
other  of  the  body."  Dr.  T.  G.  Roberts  says:  "It  was 
formerly  thought  that  alcohol  augmented  strength,  but  it 
has  been  found  by  experiment  that  the  man  who  drinks  ifc 
cannot  lift  so  heavy  a  weight  as  those  who  do  not." 

The  habitual  use  of  liquor  has  a  tendency  to  weaken 
stomach  digestion  and  decrease  the  value  of  food  con- 
sumed. Dr.  Brubaker,  of  the  Jefferson  Medical  College^ 
in  Philadelphia,  says  :  "Alcohol  deranges  the  activities 
of  the  digestive  organs,  lowers  the  body  temperature^ 
impairs  muscle  power,  diminishes  the  capacity  for  sus- 
tained mental  work,  and  leads  to  the  development  of 
structural  changes  in  the  connective  tissues  of  the  brain, 
spinal  cord,  and  other  organs."  Beer  is  often  advertised 
as  a  nutritious  drink,  but  analysis  shows  that  it  contains 
almost  no  nourishment.  All  scientists  agree  that  in 
health  beer,  whisky,  or  wine  should  not  be  used  for  food. 

Alcohol  and  Disease.  —  Very  few,  if  any,  persons  can 
drink  liquor  daily  without  causing  disease  or  a  tendency 
to  disease  in  some  of  the  tissues.  The  Committee  of 
Fifty,  as  a  result  of  years  of  investigation,  say  that  "  the 
excessive  and  continued  use  of  alcohol  affects  the  liver, 
kidneys,  heart,  blood  vessels,  and  nervous  system."  A 
considerable  amount  of  the  dyspepsia  afflicting  moderate 


ALCOHOL   AND   DISEASE  169 

drinkers  is  due  to  the  alcohol  consumed.  Most  of  the 
cases  of  shrinking  and  hardening  of  the  liver  result  from 
alcohol.  Excessive  indulgence  in  alcoholic  liquors  is  an 
important  cause  of  Bright's  disease,  and  in  those  who 
drink  large  quantities  of  beer  diseased  hearts  are  com- 
paratively frequent.  There  are  many  cases  in  which 
alcoholic  poisoning  is  evidently  the  cause  of  serious  dis- 
ease of  the  brain,  spinal  cord,  and  nerves.  One  result  of 
beer  drinking  is  the  unhealthy  production  of  fat  which 
may  occur  among  the  muscle  fibers  of  the  heart.  The 
use  of  wine  and  strong  beer  or  porter  may  produce  gout. 
The  records  of  one  of  the  large  insurance  companies  show 
that  those  not  using  alcohol  suffer  a  trifle  over  one  half  as 
many  weeks'  sickness  annually  as  those  who  are  not  ab- 
stainers. 

Physicians  state  that  pneumonia  and  tuberculosis  are 
much  more  likely  to  produce  death  in  habitual  drinkers 
than  in  others.  The  Committee  of  Fifty  finally  says:  "  The 
general  conclusion  is  that  fine  old  whiskies  and  brandies 
are  nearly  as  likely  to  produce  ill  effects  as  the  cheaper 
varieties." 

Professor  Welch,  of  the  Johns  Hopkins  University,  says : 
"  Catarrh  of  the  larynx,  pharynx,  and  bronchi  is  common 
in  alcoholic  patients."  The  famous  Dr.  Weichselbaum,  of 
Vienna,  in  speaking  of  the  effects  of  alcohol  on  the  body, 
says :  "  The  blood  gradually  becomes  sluggish  in  the  dif- 
ferent organs ;  namely,  in  the  respiratory,  digestive,  and 
nervous  systems.  Such  persons  have  an  irregular  weak 
heart,  a  chronic  laryngeal  and  bronchial  catarrh  de 
velops,  and  digestion  becomes  constantly  poorer  and 
slower ;  there  are  also  brain  and  nerve  derangements,  due 


170  ALCOHOLIC   DRINKS 

not  only  to  the  stagnation  of  the  blood,  but  also  to  the 
direct  action  of  alcohol  on  the  nerve  cells." 

Experience  clearly  proves  that  the  persons  soonest 
overcome  with  cold  in  winter  or  heat  in  summer  are  the 
users  of  alcohol.  This  is  true  because  of  the  weakening 
or  poisonous  effect  of  liquor  on  the  cells  of  the  body. 

Alcohol  and  Poverty.  —  While  the  use  of  alcohol  does 
not  always  make  one  poor,  records  show  that  thousands  of 
families  in  need  of  help  owe  their  condition  to  liquor. 
A  constant  drinker,  in  addition  to  consuming  several 
hundred  dollars'  worth  of  beer,  wine,  or  whisky  yearly, 
renders  himself  unfit  to  earn  much  money. 

The  Committee  of  Fifty,  which  spent  much  time  and 
money  to  learn  how  much  poverty  alcohol  caused,  ascer- 
tained these  facts:  About  one  fourth  of  all  cases  of 
poverty  brought  to  the  notice  of  the  Charity  Organiza- 
tions are  caused  by  alcohol,  and  more  than  one  third  of  the 
inmates  of  almshouses  are  brought  there  through  the  use 
of  liquor.  The  presence  there  of  two  fifths  of  the  males 
is  due  to  alcohol.  Of  5136  cases  of  destitute  children 
over  2300  were  found  to  owe  their  sad  state  to  the  use  of 
alcohol  by  the  parents.  The  annual  report  of  the  Bu- 
reau of  Labor  of  Massachusetts  shows  that  two  fifths  of 
all  the  paupers  in  the  almshouses  in  that  state  were 
brought  to  that  condition  by  strong  drink. 

Alcohol  and  Crime.  —  The  wide  and  accurate  scientific 
investigations  lately  completed  by  the  Committee  of  Fifty 
proves  beyond  a  doubt  that  alcohol  not  only  wrecks  the 
mind  and  body  of  thousands  yearly,  but  also  destroys 
character.  The  facts  which  they  collected  relate  to 
13,402  convicts  in  state  prisons  and  state  reformatories 


ALCOHOL  AS   A   MEDICINE  171 

in  various  portions  of  the  United  States.  The  first  cause  of 
crime  in  over  4000  of  these  was  alcohol.  Intemperance  in 
over  6000  cases  was  one  of  the  important  causes  of  crime. 

Police  records  show  that  over  1000  people  are  arrested 
every  day  in  this  country  for  drunkenness.  No  other  of- 
fense results  in  so  many  arrests.  In  fact,  drunkenness 
directly  or  indirectly  results  in  more  arrests  in  cities  with 
licensed  saloons  than  all  other  crimes  combined.  In  one 
year  there  were  arrested  for  drunkenness  in  Boston  24,000 
persons,  in  Chicago,  31,164,  in  Philadelphia  24,661,  and 
in  New  York  31,534. 

National  Loss  through  Liquor.  —  It  is  of  course  impos. 
sible  to  estimate  the  real  value  of  homes,  bodies,  and 
characters  ruined  by  strong  drink.  It  is  certain  that  over 
10,000  convicts  in  our  prisons  have  been  brought  there 
through  intemperance,  and  over  thirty  per  cent  of  the  in- 
mates of  the  almshouses  owe  their  unhappy  state  to  alcohol. 
The  disease,  suffering,  and  death  due  to  liquor  cannot  be 
accurately  computed,  but  the  amount  of  money  spent  by 
the  government  and  charitable  organizations  in  caring  for 
those  poverty-stricken  through  drink  is  not  less  than 
$100,000,000.  The  time  lost  by  the  intemperate,  if  used 
in  honest  labor,  would  be  worth  at  least  $100,000,000, 
and  the  amount  spent  annually  for  drink  is  probably  over 
$1,000,000,000. 

Alcohol  as  a  Medicine.  —  Many  years  ago  nearly  every 
family  kept  a  jug  of  whisky  in  the  house  to  be  used  in 
case  of  sickness.  To-day  very  few  educated  people  keep 
spirits  in  the  home,  because  the  latest  scientific  investiga- 
tions show  that  neither  whisky  nor  beer  is  of  much  if 
any  value  in  curing  disease.  In  most  cases  they  make  a 


172  ALCOHOLIC    DRINKS 

disease  worse.  People  should  never  use  patent  medicines, 
as  many  in  the  liquid  form  contain  from  ten  per  cent  to 
thirty  per  cent  of  .alcohol  or  other  injurious  drugs.  It  is 
due  to  the  stimulating  effects  of  the  alcohol  that  most  of 
these  medicines  make  the  consumer  feel  better  for  a  time. 
Many  people  have  contracted  the  terrible  alcohol  thirst 
by  taking  patent  medicines.  Dr.  Knopf,  an  expert  of 
international  reputation,  says:  "Alcohol  has  never  cured 
and  never  will  cure  tuberculosis.  It  will  either  prevent 
or  retard  recovery." 

Why  Alcohol  is  called  a  Poison.  —  A  poison  is  any  sub- 
stance which,  when  taken  into  the  body  in  sufficient 
quantity,  will  produce  sickness  or  death.  A  single  spoon- 
ful of  wine  or  a  small  glass  of  beer  would  not  perhaps 
make  any  adult  sick,  and  therefore  would  not  be  a  poison. 
If  this  small  amount  were  taken  daily  for  some  weeks,  it 
would  in  some  cases  so  change  the  tissues  that  there 
would  be  a  continual  longing  for  strong  drink,  and  the 
craving  might  be  so  strong  as  to  overpower  the  will. 
Under  these  circumstances  the  alcohol  acted  as  a  poison 
because  it  made  some  cells  in  the  body  sick.  A  small 
amount  of  strychnine  or  arsenic  will  not  make  one  sick, 
yet  we  call  them  poisons.  Whether  alcohol  is  a  poison  or 
a  food  is  of  little  consequence  in  judging  its  effects  on 
humanity.  The  results  of  its  use  in  any  community  are 
to  increase  crime,  poverty,  and  death,  and  on  this  account 
the  great  statesman  Gladstone  said:  "It  is  productive  of 
greater  evils  than  the  combined  scourges  of  war,  famine, 
and  pestilence." 

Danger  from  the  Use  of  Alcohol.  —  Some  persons  can 
drink  beer  or  wine  occasionally  without  perceptibly  injur- 


DANGER   FROM   THE   USE   OF   ALCOHOL  173 

ing  their  health,  yet  their  example  may  cause  many  to 
indulge  who  will  be  led  on  little  by  little  until  they  be- 
come drunkards.  Many  who  do  not  continue  until 
drunkenness  results,  weaken  their  bodies  and  minds,  and 
make  themselves  more  liable  to  disease  and  crime.  Re- 
ports secured  from  various  parts  of  the  United  States 
show  that  at  least  one  in  every  ten  occasional  drinkers 
becomes  positively  intemperate.  Many  people,  after  be- 
coming accustomed  to  the  use  of  alcohol,  are  unable  to 
stop  drinking  without  being  placed  in  confinement  and 
kept  there  until  the  tissues  have  again  become  well.  The 
tissues  of  the  young  are  affected  much  more  quickly,  and 
an  incontrollable  appetite  developed  much  sooner  than  in 
persons  past  fifty. 

The  younger  the  individual  the  greater  is  the  danger 
in  taking  an  occasional  drink.  Helenius,  in  a  paper  read 
at  the  University  of  Copenhagen  in  1902,  showed  that 
alcohol  had  fatally  poisoned  during  the  nineteenth  cen- 
tury 7,500,000  persons  in  the  civilized  countries  of  Europe, 
America,  and  Australia.  All  of  these  were  at  one  time 
occasional  drinkers.  Observation  shows  that  the  army 
of  drunkards  in  this  nation  receives  all  of  its  recruits 
from  those  who  are  occasional  drinkers.  The  one  safe 
plan,  then,  is  never  to  take  the  first  drink.  A  young  man 
can  display  no  greater  patriotism  than  to  fight  against 
that  which  brings  to  his  country  woe,  want,  and  poverty. 
To  be  a  total  abstainer,  that  is,  to  refuse  to  use  liquor  at 
any  time,  requires  the  courage  of  principle  that  dares  to 
do  right  in  the  face  of  scorn,  a  kind  of  courage  that  may 
be  called  the  perfection  of  humanity. 


174  ALCOHOLIC   DRINKS 


Questions 

1.  How  is  alcohol  made?  2.  Tell  what  you  know  about  the  yeast 
plant.  3.  Explain  how  distilled  liquors  are  made.  4.  Name  some 
distilled  liquors.  5.  How  do  fermented  liquors  differ  from  malt 
liquors  ?  6,  Name  several  malt  liquors.  7.  What  drink  contains  the 
most  alcohol  ?  8.  Name  some  drinks  containing  a  small  amount  of  alco- 
hol. 9.  What  drinks  contain  from  fifteen  per  cent  to  thirty  per  cent  of 
alcohol  ?  10.  How  much  do  our  people  pay  yearly  for  alcoholic  patent 
medicines?  11.  What  facts  show  that  alcohol  unfits  men  for  doing 
their  best  work  ?  12.  How  many  men  in  our  country  are  drinking  to 
such  excess  as  to  injure  health?  13.  Give  evidence  showing  that 
alcohol  does  not  enable  one  to  do  more  work.  14.  State  ten  facts 
showing  that  alcohol  may  produce  ill  health.  15.  Why  do  not  drinkers 
resist  disease  as  well  as  abstainers?  16.  Give  facts  showing  that 
alcohol  has  much  to  do  with  poverty.  17.  To  what  extent  does  alcohol 
contribute  to  crime  ?  18.  How  much  does  this  nation  lose  through 
liquor?  19.  When  may  alcohol  be  considered  a  poison?  20.  Why  is 
it  not  wise  to  take  the  first  drink  in  youth  ? 

Suggestions  for  the  Teacher 

1.  Prepare  three  glasses  with  an  inch  of  soil  in  each.     Moisten  the 
soil  of  number  1  with  beer,  number  2  with  a  solution  of  one  teaspoon- 
ful  of  beer  and  two  teaspoonfuls  of  water,  and  number  3  with  pure 
water.     In  each  plant  several  seeds  of  corn,  wheat,  or  beans.     Keep 
the  glasses  covered  with  a  piece  of  glass,  and  place  them  in  a  light 
and  warm  room,  but  not  in  direct  sunlight.      Observe  the  growths 
during  the  following  weeks,  and  ask  the  pupils   to  tell  what  the 
experiment  teaches. 

2.  Secure  two  small  potted  plants  of  the  same  size,  and  for  two  or 
three  weeks  keep  the  soil  of  one  moistened  with  water  and  the  other 
with  equal  parts  of  water  and  beer.     Note  the  results. 


XVI.    THE    EXCRETORY   SYSTEM 


Excretions.  —  The  excretions  of  the  body  such  as  sweat 
and  urine  differ  from  the  secretions  like  gastric  juice  and 
saliva  in  that  they  are  of  no  further  use  to  the  system. 
Every  active  cell  is  giving  off  several  substances  as  a  re- 
sult of  the  life  processes.  The  carbon  dioxide  is  carried 

by  the  blood   to  the   lungs,  and     

through  them  is  expelled.  Waste 
flesh  is  constantly  passing  out  of 
every  living  cell,  and  would  in  a 
few  hours  poison  the  body  if  it- 
were  not  taken  up  by  the  capil- 
laries of  the  circulatory  system 
and  transported  to  the  kidneys 
and  sweat  glands  to  be  separated 
from  the  blood. 

The  Kidneys.  —  These  are  two 
bean-shaped  organs  a  little  longer 
than  the  middle  finger.  They  lie 
against  the  posterior  surface  of 
the  abdominal  cavity,  one  on  either  side  of  the  backbone 
just  below  the  diaphragm.  Any  vessel  or  nerve  dis- 
tributed to  the  kidney  is  named  renal,  because  the  Latin 
word  renalis  means  pertaining  to  the  kidney.  The  renal 
artery  comes  direct  from  the  aorta,  and  the  renal  vein 
leads  the  blood  to  the  vena  cava. 

175 


FIG.  112.  —  Human   kidney. 
u,  ureter. 


176 


THE   EXCRETORY   SYSTEM 


Within  the  kidney  the  artery  divides  like  the  branches 
of  a  tree,  and  each  of  the  thousands  of  branchlets  ends  in 
a  very  tiny  ball  of  capillaries.  There  are  about  a  half 
million  of  these  balls.  Every  one  of  them  is  enveloped 
by  the  enlarged  end  of  a  minute  crooked  tube,  which 

unites  with  several  of  the 
thousands  of  other  similar 
tubes  to  carry  the  urine  to 
the  inner  edge  of  the 
kidney  (Fig.  114).  Here 
a  somewhat  funnel-shaped 
cavity,  the  pelvis,  receives 
the  urine  and  lets  it  pass 
into  the  ureter.  This  is 
a  tube  leading  from  the 
kidney  to  the  bladder,  a 

FIG.  113. -Section  of  a  kidney,     ar,  globular       ^ac      which  Is 

artery;  v,  vein;  6,  pel  vis;  u,  ureter;  larger    than    the    fist.  It 

py,  one  of  the  several  places  where  -, .         .        ,-,        -,  £ 

the  thousands  of  tuhes  represented  ll6S    m    the    loW6r  Part  °f 

by  the  fine  black  lines  empty  into  the  abdomen. 

the  pelvis'  How  the  Kidneys  Work. 

—  In  the  blood  coming  to  the  kidneys,  there  is  much 
water,  mineral  matter,  and  waste  flesh  called  urea.  By 
the  pressure  of  the  blood  and  the  living  action  of  the 
kidney  cells  forming  the  fifteen  miles  of  tubes,  the  water, 
salts,  and  urea  are  passed  through  the  blood  capillaries 
into  the  kidney  tubes,  and  thence  on  to  the  pelvis,  ureter, 
and  bladder.  Although  the  nutrition  for  the  tissues  is 
in  the  blood,  yet  the  cells  of  the  kidney  tubes  prevent 
it  from  being  excreted,  and  cause  to  pass  through  them 
only  that  which  would  be  harmful  if  left  in  the  system. 


THE    KIDNEY    EXCRETION 


177 


Each   cell   seems   to   act  with   wonderful   precision,  and 
makes  no  error  unless  it  is  overworked  or  made  sick. 

The  Kidney  Excretion.  — One  twenty-fifth  of  the  urine 
consists  of  solids,  and  the  remainder  is  water.     Of  the 

solids  more    than   half     , . 

is  composed  of  urea. 
The  amount  of  broken- 
down  flesh  passing  off 
from  the  system  daily 
in  this  way  is  about 
one  ounce.  The  more 
water  one  drinks,  the 
more  the  kidneys  ex- 
crete, and  if  one  uses 
very  little  water,  there 
is  sometimes  not  suf- 
ficient fluid  to  wash 
properly  the  waste  sub- 
stances from  the  tissues 
and  through  the  kid- 
neys. Illness  then  re- 
sults. 

A    good    preventive 
of  rheumatism,  and  con- 


FIG.  114.  —  Diagram  of  the  part  of  the 
kidney  between  the  letters  m  and  n  in 
Figure  113.  ar,  artery ;  v,  vein ;  t ,  ball  of 
capillaries;  n,  capillaries.  From  these 
two  sets  of  capillaries  the  urine  is  taken 
into  the  tube  xc  and  d. 


stipation    or    clogging 

of  the  lower  bowel,  is 

the  drinking  of  much 

pure   soft  water.      A   grown  person  should   consume  at 

least    a    quart    of    milk    or   water    daily,    and   it   would 

result  in  better  health  if  two  quarts  of  fluid  were  taken 

daily. 

X>AV.   PHYS.  12 


178  THE   EXCRETORY   SYSTEM 

Alcohol  and  the  Kidneys.  —  When  the  cells  forming  the 
tubes  of  the  kidneys  become  sick,  they  allow  part  of  the 
albumen  of  the  blood  to  escape  with  the  urine,  resulting 
in  serious  ill  health.  This  condition  is  known  as  inflam 
mation  of  the  kidneys,  or  Bright* 8  disease.  It  is  sometimes 
caused  by  alcoholic  drink.  It  may  also  be  brought  on  in 
some  persons  by  eating  too  much  meat  or  other  nitroge- 
nous foods  for  days  and  weeks  in  succession,  while  taking 
but  little  exercise.  It  sometimes  follows  scarlet  fever 
and  other  diseases  where  there  is  a  great  deal  of  tissue 
waste  which  must  be  passed  out  through  the  kidneys. 
In  any  case  the  cells  of  the  kidneys  become  sick  because 
they  are  overworked.  Bright's  disease  is  twice  as  com 
mon  now  as  it  was  a  quarter  of  a  century  ago,  and  scien- 
tists agree  that  this  increase  is  due  in  part,  at  least,  to  the 
increased  use  of  the  light  alcoholic  drinks.  It  caused 
nearly  100,000  deaths  in  the  United  States  in  the  year 
1905. 

Structure  of  the  Skin.  —  The  skin  is  composed  of  two 
layers,  known  as  the  cuticle^  or  epidermis,  and  the  cutis,  or 
true  skin.  The  cuticle  consists  of  epithelial  cells,  the  sev- 
eral upper  layers  of  which  have  no  nuclei  and  are  flat. 
The  deeper  cells  are  cubical.  No  blood  vessels  or  nerves 
are  present,  but  every  square  inch  is  pierced  by  a  hundred 
or  more  tubes  leading  from  sweat  glands.  Under  a  mag- 
nifying glass,  the  mouths  of  these  appear  as  minute  pits 
arranged  in  rows  on  the  little  ridges  in  the  palm  of  the 
hand.  The  cells  on  the  surface  of  the  epidermis  are  be- 
ing constantly  shed,  while  new  ones  are  being  developed 
from  the  lower  layers.  In  caterpillars,  crabs,  frogs,  and 
snakes  the  cells  on  the  surface  of  the  skin  hold  together 


STRUCTURE   OF   THE   SKIN 


179 


and  are  shed  in  one  entire  mass.  The  use  of  the  epider- 
mis is  to  prevent  injuries  to  the  more  delicate  structures 
beneath  and  to  keep  germs  from  entering  the  tissues. 


FIG.  115.  —  Section  through  the  skin,  a,  dead  epidermis;  d,  live  epidermis : 
all  below  is  the  derma  or  true-skin,  ar,  artery  seen  dividing  into  capillaries 
again  uniting  to  form  a  vein ;  e,  sweat  glands ;  /,  fat  cells ;  n,  nerve  endings. 

The  cutis,  or  derma,  lies  beneath  the  epidermis  and 
consists  of  a  tough  elastic  network  of  fibers  mingled  with 
a  few  cells.  In  it  are  numerous  capillaries  and  the  end- 


180  THE   EXCRETORY   SYSTEM 

ings  of  nerves,  some  of  which  are  acted  on  by  heat,  some 
by  cold,  and  others  by  touch.  The  skin  is  bound  to  the 
underlying  muscles  and  fatty  tissue  by  a  loose  elastic 
connective  tissue. 

Use  of  the  Skin.  —  The  epidermis  prevents  injury  to  the 
more  delicate  structures  beneath.  Touching  the  naked 
nerve  endings  would  cause  pain,  and  contact  with  rough 
material  would  destroy  them  and  break  the  delicate  walls 
of  the  blood  capillaries.  This  may  be  observed  on  any  raw 
surface.  The  dry  and  horny  nature  of  the  epithelium 
excludes  germs  and  poisons  with  which  the  body  frequently 
comes  in  contact. 

The  derma,  or  cutis,  is  the  seat  of  the  important  senses 
of  pressure,  pain,  and  temperature.  We  receive  our 
knowledge  of  pressure  and  temperature  entirely  through 
nerve  endings  in  the  cutis,  but  nerve  endings  for  the  sense 
of  pain  are  present  all  over  the  body.  The  cutis  is  also 
an  important  means  of  regulating  the  body  heat.  When 
the  body  becomes  hot,  the  capillaries  of  the  skin  enlarge 
so  that  the  hot  blood  can  come  to  the  surface  and  be 
cooled.  Evaporation  of  the  sweat  also  cools  the  body. 

Injuries  to  the  Skin.  —  Slight  pressure  or  friction  for  a 
long  time  on  the  skin  causes  the  epidermis  to  become 
thicker.  For  this  reason  it  is  more  than  twice  as  thick 
on  the  palms  of  the  hands  and  the  soles  of  the  feet  as  else- 
where. Hard  pressure  or  friction  will  sometimes  produce 
a  blister  or  a  corn.  A  blister,  which  may  also  be  made  by 
the  application  of  mustard  or  other  irritating  substance, 
is  a  portion  of  the  epidermis  separated  from  its  deepest 
layer  by  a  collection  of  lymph  having  oozed  out  of  the 
underlying  vessels. 


THE    SWEAT    GLANDS 


181 


A  corn  is  a  thickening  of  a  spot  of  epidermis  so  that  it 
presses  on  the  tissues  beneath.  The  best  remedy  for  a 
corn  is  to  soak  the  feet  in  warm  water  and  then  with  a 
razor  or  sharp  knife  pare  off  the  thickened  cuticle,  being 
careful  not  to  cut  deep  enough  to  cause  pain.  The  pres- 
sure of  the  shoe  may 
then  be  removed  by 
pasting  on  one  side 
of  the  corn  a  piece 
of  thick  cloth  with 
dried  mucilage  on 
one  surface.  Reg- 
ular corn  rings  may 
be  purchased  at  the 
drug  store  for  the 
same  purpose. 

Sometimes  large 
areas  of  skin  are  de- 
stroyed by  burning 
or  otherwise.  It  is 
then  necessary  to 
cut  small  bits  of 
skin  from  other  parts  of  the  body  or  from  another  person's 
body  and  lay  them  upon  the  raw  surface.  They  will 
absorb  the  lymph  diffusing  from  the  capillaries,  and  the 
cells  will  multiply  in  a  few  weeks  so  as  to  cover  the  naked 
tissues.  This  is  called  skin  grafting. 

The  Sweat  Glands.  —  There  are  about  2,000,000  sweat 
glands  distributed  in  the  deeper  layers  of  the  dermis. 
They  are  thickest  in  the  palms  of  the  hands,  on  the  soles 
of  the  feet,  and  on  the  forehead.  Each  gland  consists  of 


FIG.  116.  —  Mouths  of  sweat  glands.    Magnified. 


182  THE   EXCRETORY   SYSTEM 

a  minute  coiled  tube  in  the  cutis  and  a  duct  extending  in 
a  slightly  wavy  course  through  the  epidermis  to  the  sur- 
face (Fig.  115).  With  a  magnifying  glass  these  openings 
may  be  seen  in  the  hand.  These  glands  give  forth  a  fluid 
called  perspiration.  Their  activity  is  greatly  increased  by 
heat  or  exercise. 

Perspiration.  —  The  amount  of  sweat  given  out  by  a 
laboring  man  in  warm  weather  may  be  as  much  as  one 
gallon  daily.  The  average  quantity  excreted  by  an  adult 
is  a  little  less  than  a  quart  in  twenty-four  hours.  More 
than  ninety-nine  per  cent  of  sweat  is  water.  A  slight 
amount  of  urea,  common  salt,  and  a  few  other  substances  are 
present.  The  chief  use  of  the  perspiration  is  to  control  the 
temperature  of  the  body.  Heat  arouses  certain  nerves 
which  control  the  sweat  glands  and  makes  their  excretions 
flow  out  in  larger  quantities  on  the  surface  of  the  body. 
Here  it  evaporates  and  thus  cools  the  skin.  One  seventh 
of  the  heat  of  the  body  is  lost  by  the  evaporation  of  the 
sweat.  Dr.  Zuntz  tells  of  a  man  who  had  no  sweat 
glands,  and  was  unable  to  work  in  the  hot  weather  be- 
cause the  temperature  of  his  body  became  too  high. 
Sitting  in  a  wind  after  sweating  often  causes  a  cold. 

The  Sebaceous  or  Oil  Glands.  —  These  are  present  in 
the  skin  wherever  hair  occurs,  whether  it  is  long,  as  upon 
the  head,  or  pale  and  short,  as  on  other  parts  of  the  body. 
Each  gland,  scarcely  as  large  as  the  point  of  a  pin  and 
somewhat  like  a  bunch  of  grapes,  opens  by  a  single  duct 
near  the  top  of  the  sac  inclosing  the  root  of  the  hair. 
The  secretion  is  an  oily  semiliquid  mass  which  sets,  upon 
exposure  to  the  air,  into  a  cheesy  mass,  as  seen  in  the 
pimples  frequently  occurring  on  the  face.  These  pimples 


BALDNESS   AND   GRAY   HAIR 


183 


may  be  avoided  in  many  cases  by  eating  but  little  meat, 
refraining  from  sweets  and  pies,  and  taking  much  out- 
door exercise. 

The  secretion  of  the  sebaceous  glands  is  of  some  use  in 
keeping  the  skin  soft  and  making  the 
hair  more  pliable.  It  is,  in  fact, 
nature's  hair  oil,  and  no  other  dress- 
ing for  the  hair  should  be  used. 
The  glands  may  be  made  more 
active  by  massaging  or  gentle  pinch- 
ing of  all  parts  of  the  scalp  daily. 

The  Hair.  —  The  hair  is  composed 
of  minute  horny  scales  and  is  widely 
distributed  over  the  body.  Each 
hair  is  situated  in  a  tubelike  sac 
called  the  follicle,  made  by  the  dip- 
ping down  of  the  epidermis  into  the 
lower  tissues.  At  the  bottom  of  the 
follicle  is  a  little  knob,  the  papilla, 
made  of  capillaries  and  other  tissue. 
It  is  from  this  papilla  that  a  new 
hair  grows  as  often  as  the  old  one  is 
pulled  out.  The  little  teacuplike 
cavity  in  the  end  of  the  hair  fits  over 
the  papilla,  whereby  nourishment 
from  the  blood  readily  reaches  the 
hair  (Fig.  117). 

Baldness  and  Gray  Hair.  —  The  falling  out  of  the  hair 
does  not,  except  in  rare  cases,  result  from  bacteria,  mi- 
crobes, or  any  kind  of  germs,  but  is  due  to  a  lack  of 
nourishment  furnished  by  the  papilla  at  its  root.  If  the 


s 


FIG.  117.  —  Section  of  the 
scalp,  magnified,  h, 
hair;  w,  hair  sac;  «, 
sebaceous  gland ;  m, 
muscle  which  may 
sometimes  cause  the 
hairs  to  stand  erect. 


184  THE    EXCRETORY    SYSTEM 

papilla  is  dead,  no  substance  will  cause  the  hair  to  grow, 
and  therefore  no  attention  should  be  paid  to  the  numerous 
advertisements  offering  for  sale  drugs  or  apparatus  that 
will  make  hair  develop  on  a  bald  he.ad.  The  fact  that 
Indians  and  others  who  never  wear  close-fitting  hats  do 
not  become  bald  indicates  that  the  pressure  of  the  hat 
about  the  head,  thereby  shutting  off  to  some  extent  the 
blood,  may  be  one  cause  of  baldness.  Another  cause  may 
be  the  exclusion  of  fresh  air  from  the  head. 

Dandruff  commonly  results  from  an  unhealthy  condi- 
tion of  the  cells  of  the  scalp.  This  may  be  remedied  by 
washing  the  scalp  thoroughly  with  tepid  water  and  any 
good  toilet  soap  weekly  or  bi-weekly.  The  soap  should  be 
well  washed  out  with  soft  water,  and  the  hair  then  dried  as 
quickly  as  possible.  The  tendency  to  baldness  is  often 
hereditary,  and  frequently  nothing  will  prevent  it.  In 
many  cases,  the  hair,  when  beginning  to  fall  out,  may  be 
invigorated  by  massaging,  that  is,  pinching  and  wrinkling 
together  various  portions  of  the  scalp  a  few  minutes  daily. 

Fright,  anxiety,  or  great  care  may  turn  the  hair  gray  in 
a  few  weeks  or  even  a  single  night,  but  usually  the  gray 
color  appears  gradually  after  the  age  of  forty.  It  is  due 
to  air  taking  the  place  of  the  pigment  in  the  central  por- 
tion of  the  hair.  There  is  no  way  of  preventing  the  hair 
from  becoming  gray  except  by  dyeing  it  frequently,  a  pro- 
cedure which  usually  injures  the  hair  and  sometimes  the 
general  health. 

The  Complexion.  —  The  great  difference  in  the  com- 
plexion of  persons  is  due  largely  to  the  pigment  lying  in 
the  lower  part  of  the  epidermis.  In  negroes  there  is 
much  of  the  pigment,  and  it  is  very  dark.  In  people  of 


THE   COMPLEXION 


185 


light  complexion  only  a  little  pigment  is  present.  Tan- 
ning is  the  temporary  development  of  extra  pigment 
influenced  by  the  rays  of  the  sun. 

The  skin  cannot  be  made  soft,  beautiful,  and  white 
by  means  of  paints  and 
powders.  Some  of  them 
contain  poisons,  such 
as  arsenic,  and  more- 
over they  are  likely  to 
clog  the  openings  of  the 
glands,  eventually  giv- 
ing an  ugly  complexion. 
Washing  the  skin  with 
soft  water  and  soap, 
eating  fruits  instead  of 
sweetmeats,  drinking 
much  water  or  lemon- 
ade, taking  plenty  of 
exercise  in  the  open  air, 
and  keeping  the  mind 
free  of  evil  thoughts 
by  thinking  good  ones  are  certain  aids  in  producing  a 
pleasing  complexion  and  countenance. 

Hair  growing  on  the  face  or  in  other  regions  where  it 
is  not  wanted  can  be  permanently  removed  only  by  means 
of  the  electric  needle.  Therefore,  it  is  foolish  to  give 
heed  to  any  of  the  numerous  offers  made  by  quacks  in  the 
newspapers  to  sell  a  drug  that  will  permanently  remove 
hair.  The  preparations  so  much  advertised  usually  con- 
tain a  compound  of  sulphur,  which  will  dissolve  the  hair 
on  the  surface  but  will  not  kill  the  roots.  If  applied 


FIG.  118.  —  Hand,  showing  the  effects  of 
chewing  off  the  finger  nails. 


186 


THE   EXCRETORY   SYSTEM 


I 


several  times,  the  skin  becomes  very  sore  and  the   hair 
tends  to  become  thicker. 

The  Nails.  —  The  nails  are  hardened  epidermis.  They 
protect  the  ends  of  the  fingers  if  they  are  not  cut  too 
short.  The  very  bad  habit  of  chewing  off  the  ends  of  the 
nails  causes  short  and  blunt  fingers.  The  nails  should 

be  filed  off  every  morn- 
ing even  with  the  finger 
tips,  and  the  dirt  should 
be  removed  from  be- 
neath the  nails  each  time 
§  after  washing  the  hands. 

t  Growths  on  the  Skin. 

Warts  are  overgrowths 
of  the  epithelial  cells. 
Their  cause  is  not 
known.  They  are  not 
harmful  and  may  be 
easily  removed  by  a 
physician,  but  are  in  no 
way  affected  by  any 
words  a  fortune  teller 
can  say.  Moles  are  slight  elevations  of  the  epidermis 
containing  an  increased  growth  of  hair.  They  are  usually 
inherited. 

Cancer  is  probably  not,  as  was  once  thought,  the  result 
of  germs  growing  in  the  tissues,  but  is  due  to  the  cells  of 
the  body  becoming  deranged.  They  multiply  rapidly  and 
consume  the  other  tissues,  eating  away  blood  vessels  and 
nerves,  so  that  in  a  year  or  two  death  often  results.  Can- 
cer is  not  contagious.  No  one  should  pay  any  attention 


FIG.  119. — Hand,  showing  nails  properly 
cared  for. 


THE  COLD   BATH  187 

to  the  numerous  advertisements  by  doctors  offering  to  cure 
cancer.  Many  tumors  are  called  cancers  and  are  easily 
cured,  while  some  cancers  cannot  be  cured  by  any  means. 
Reliable  physicians  and  surgeons  never  advertise  cures. 
It  is  best  to  follow  the  advice  of  the  family  physician. 

The  Hot  Bath.  —  Cold  water  will  not  cleanse  the  body 
thoroughly,  and  therefore  every  one  should  bathe  the 
entire  body  at  least  once  a  week  in  hot  water,  using  soap 
and  friction  to  remove  not  only  dirt  but  also  the  outer 
dead  skin  likely  to  clog  the  pores.  Such  bathing  is  an  aid 
to  health  and  a  preventive  of  the  unpleasant  odors  given 
off  from  an  uncleanly  body.  The  feet  and  certain  other 
portions  of  the  body  should  be  washed  daily  to  be  kept 
odorless.  The  proper  time  for  a  hot  bath  is  at  night,  as 
the  heat  draws  the  blood  away  from  the  brain,  makes  it 
less  active,  and  tends  to  produce  sleep.  The  bath  should 
not  be  taken  just  after  a  meal,  as  the  blood  is  drawn 
away  from  the  digestive  organs  to  the  surface  of  the 
body. 

The  Cold  Bath.  —  The  hot  bath  may  be  taken  as  hot  as 
one  can  bear  it,  but  the  cold  bath  should  be  from  about 
sixty-eight  to  seventy-eight  degrees.  The  most  favorable 
time  for  a  cold  bath  is  immediately  upon  rising  in  the 
morning  or  just  after  exercising,  when  the  body  is  warm. 
It  should  not  last  longer  than  one  or  two  minutes,  after 
which  the  body  ought  to  be  briskly  rubbed  with  a  rough 
towel.  If  a  tub  or  regular  shower  bath  cannot  be  had, 
almost  equal  results  may  be  reached  by  standing  in  a  wash 
bowl  or  small  tub  and  pouring  the  cold  water  on  the 
shoulders  and  letting  it  run  down  over  all  parts  of  the 
body. 


188  THE  EXCRETORY   SYSTEM 

Cold  bathing  is  of  great  use  in  treating  patients  with 
nervous  disorders  or  consumption,  and  in  the  healthy  it 
tones  up  the  system,  and  is  a  great  preventive  of  colds  if 
taken  daily.  Within  a  few  minutes  after  leaving  the 
cold  bath,  reaction  should  occur,  when  the  capillaries  and 
small  arteries  enlarge,  the  skin  flushes,  and  there  is  a 
general  sense  of  warmth  and  well-being. 

Swimming  and  Bathing.  —  Swimming  is  one  of  the  most 
helpful  forms,  of  exercise.  It  should,  however,  usually 
not  be  indulged  in  more  than  once  a  day,  and  then  for  a 
period  not  exceeding  a  half  hour.  When  one  is  jumping 
about  or  swimming,  the  heat  produced  by  the  muscular 
exercise  counteracts  the  effect  of  the  cold  water  on  the 
skin. 

It  is  the  duty  of  every  one  to  learn  to  swim.  The 
census  report  shows  that  during  the  years  1900  to  1904 
about  40,000  people  lost  their  lives  by  drowning.  The 
ability  to  swim  would  doubtless  have  saved  a  large  per- 
centage of  these.  It  is  important  to  remember  that  there 
is  danger  in  going  into  the  water  to  swim  when  one  is 
very  tired,  as  the  weary  muscles  are  likely  to  go  into 
cramps.  The  safest  plan  is  never  to  go  alone  into  water 
over  one's  head.  Swimming  just  before,  or  sooner  than 
two  hours  after,  a  heavy  meal  is  unwise. 

Clothing  and  Health. —  The  chief  use  of  clothing  is  to  aid 
the  body  in  keeping  a  constant  temperature  and  thus  pre- 
vent sickness.  Woolen  clothing  is  warmer  than  cotton  or 
linen  clothing  because  it  contains  many  meshes  or  tiny 
open  spaces  filled  with  air.  This  air  prevents  the  escape 
of  heat  from  the  body.  Therefore  the  clothing  for  cold 
weather  should  generally  be  of  wool.  Since  woolen  goods 


ALCOHOL  AND  THE  SKIN  189 

do  not  absorb  and  pass  off  the  sweat  so  quickly  as  cotton 
or  linen  cloth,  the  clothing  worn  next  to  the  skin  by  vig- 
orous and  healthy  persons  should  consist  of  loosely  woven 
cotton  or  linen  material  for  all  seasons.  As  the  clothing 
worn  next  to  the  skin  absorbs  the  excretions  coming  from 
the  sweat  pores,  it  should  be  frequently  washed.  It  is 
wise  to  change  the  underclothing  weekly  in  winter  and 
twice  weekly  in  summer. 

The  body  can  be  made  comfortable  while  out-of-doors 
in  cold  weather,  by  wearing  an  overcoat  or  wrap.  The 
feet  should  be  protected  from  the  wet  by  rain-proof  shoes 
or  overshoes.  One  should  never  sit  in  wet  clothing  but 
exercise  until  it  can  be  exchanged  for  dry  garments. 

Alcohol  and  the  Skin.  —  Repeated  indulgence  in  the  use 
of  alcoholic  drink  makes  the  skin  of  the  face  puffy,  and 
may  give  to  it  a  blotched  appearance,  so  characteristic 
of  the  confirmed  drunkard.  Alcohol  enlarges  the  arteries 
and  capillaries  of  the  skin,  and  thus  makes  the  face  red, 
and  in  cold  weather  cools  the  body  very  rapidly,  because 
so  much  of  the  warm  blood  is  brought  to  the  surface.  In 
health  seventy-five  per  cent  of  the  heat  leaving  the  body  is 
lost  by  passing  off  from  the  capillaries  of  the  skin.  The 
use  of  alcohol  may  increase  this  loss  of  heat  by  ten  per  cent. 
The  shivering  fits  on  recovery  from  drunkenness,  which 
frequently  occur,  are  due  to  the  fact  that  the  body  has  lost 
a  considerable  amount  of  heat.  The  lowering  of  the  tem- 
perature of  the  body  by  alcoholic  drink  may  result  in  death. 
During  a  very  cold  night  in  winter  several  of  a  group  of 
men,  camping  in  the  mountains  in  the  West,  drank  consid- 
erable whisky  before  retiring,  and  as  a  result  froze  to 
death.  Those  who  refrained  from  drink  survived. 


190  THE   EXCRETORY   SYSTEM 


Questions 

1.  What  are  excretions  ?  2.  Describe  the  kidneys.  3.  How  do  the 
kidneys  work?  4.  Why  should  much  water  be  drunk?  5.  Ex- 
plain the  effect  of  alcohol  on  the  kidneys.  6.  Describe  the  epidermis. 
7.  Describe  the  cutis.  8.  Of  what  use  is  the  skin  ?  9.  How  does  a  corn 
differ  from  a  blister  ?  10.  Describe  the  sweat  glands.  11.  State  five 
facts  concerning  perspiration.  12.  Describe  the  oil  glands.  13.  What 
may  cause  baldness?  14.  Give  the  cause  and  cure  for  common 
dandruff.  15.  How  may  the  complexion  be  improved  ?  16.  Describe 
the  care  of  the  nails.  17.  Why  should  one  never  employ  a  doctor  ad- 
vertising to  cure  cancer?  18.  Of  what  use  is  a  hot  bath?  19.  How 
often  and  when  should  a  hot  bath  be  taken  ?  20.  Why  should  most 
people  take  a  cold  bath  daily  ?  21.  What  care  should  be  observed 
when  swimming  ?  22.  Explain  the  influence  of  alcohol  on  the  skin. 


Suggestions  for  the  Teacher 

The  teacher  should  take  this  opportunity  to  impress  upon  the 
pupils  the  necessity  of  personal  cleanliness,  and  the  importance  of 
caring  properly  for  the  nails  and  hair.  Some  of  the  pupils  may  be 
asked  to  give  their  personal  experience  in  reference  to  the  benefit 
derived  from  the  hot  and  cold  baths. 

To  show  that  wool  is  more  serviceable  than  cotton  in  keeping 
the  body  warm,  heat  two  small  tin  cans  of  water.  Wrap  around  one 
a  piece  of  cotton  cloth  and  around  the  other  a  piece  of  woolen  cloth 
weighing  the  same  as  the  cotton  cloth.  Let  the  pupils  note  the 
difference  in  temperature  by  touching  the  water  in  each  can  at  the 
end  of  a  half  hour  or  more. 

To  prove  that  wet  clothing  cools  the  body  quickly,  secure  two 
pieces  of  cotton  cloth  of  the  same  size  and  two  jars  of  warm  water. 
Wet  one  cloth  and  wrap  it  around  one  of  the  jars  and  put  the  other 
cloth  dry  about  the  other  jar.  At  the  end  of  a  half  hour  test  with 
the  finger  which  jar  of  water  is  the  cooler.  The  teacher  may  save 
some  of  the  children  from  many  colds  and  serious  sickness  by  im- 
pressing upon  them  the  danger  of  sitting  still  while  the  clothing  is  wet 


XVII.     THE    OSSEOUS   SYSTEM,   OR  BONES 

The  Use  of  Bones.  —  The  bones  of  the  body  are  neces- 
sary for  its  support  and  also  to  enable  it  to  move.  The 
muscles,  which  are  made  to  act  by  the  nerves,  pull  upon 
some  of  the  bones  so  as  to  move  them  in  various  ways. 
The  bones  protect  the  vital  organs,  such  as  the  brain, 
spinal  cord,  lungs,  and  heart.  All  the  red  blood  cor- 
puscles, and  many  of  the  white  ones,  are  made  in  the  red 
bone  marrow,  occupying  a  portion  of  the  interior  of  the 
bones. 

The  Parts  of  the  Skeleton.  —  There  are  about  200  bones 
in  the  body.  These  joined  together  in  their  natural  rela- 
tions form  the  skeleton.  It  is  divided  into  the  skull,  or 
bones  of  the  head,  trunk,  and  extremities^  according  to  the 
table  given  on  the  next  page. 

The  cranium  is  composed  of  the  bones  surrounding  the 
brain,  while  the  other  bones  of  the  head  form  the  face. 
The  spinal  column  is  not  a  single  bone,  but  is  constructed 
of  a  chain  of  24  bones,  called  vertebrae,  in  addition  to  the 
sacrum  and  coccyx  formed  of  vertebrae  grown  together. 
Within  a  canal  extending  through  the  vertebrae  lies  the 
spinal  cord.  The  same  bones  present  in  the  human 
skeleton  are  also  found  in  the  dog  or  cat,  and  therefore 
the  skeleton  of  these  animals  often  discovered  in  the 
woods  or  fields  may  be  used  for  study. 

191 


192 


THE   OSSEOUS   SYSTEM,    OR   BONES 


3 


FIG.   120.  —  Human    skeleton.     See 
description  in  next  column. 


FIG.  121.  —  Side  view  of  ver- 
tebral column  and  skull. 
See  description  below. 

FIGS.  120-121.  —  a,  tarsals ;  c,  meta- 
cnrpals ;  d,  clavicle ;  /,  femur ;  ji,  fib- 
ula; h,  humerus;  i,  innominate  or 
hip  bone ;  k,  patella  or  kneecap ;  m, 
metatarsals ;  p, phalanges;  r, radius; 
s,sacrum;  £,tibiaorshinbone;  w,ulna. 

1,  frontal  bone ;  2,  parietal ;  3,  occip- 
ital ;  6,  orbital  cavity ;  7,  temporal 
bone;  8,  maxillary;  9,  malar;  16, 
mandible ;  37,  cervical  or  neck  verte- 
brae ;  40,  dorsal  or  thoracic  vertebrae ; 
41,  lumbar  vertebrae ;  42,  sacrum ; 
43,  coccyx ;  38  and  39,  spines  of  axis 
and  atlas. 


KINDS   OF   BONES 


193 


The  Skull 

or 

Bones 
of  the 
Head 


Bones  of  the 
Trunk 


Bones  of  the 

Upper 
Extremity 


Bones  of  the 
Lower  Ex- 
tremity 


Cranium 


TABLE  OF  BONES 


frontal  1 
parietal  2 
temporal  2 
occipital  1 
ethmoid  1 
sphenoid  1 


Face 


Spinal  column 
or  backbone 

Other  bones  of 
,    the  trunk 


Shoulder  girdle 

Arm 

Forearm 

Wrist 
Hand 
Fingers 

Leg 

Ankle 

Foot 

Toes 


nasal  2 

inferior  turbinated  2 

lachrymal  2 

maxilla  or  upper  jaw  2 

mandible  or  lower  jaw  1 

palate  2 

malar  or  cheek  bone  2 

vomer  1 

hyoid  1 

["vertebra  24 

<  sacrum  1 

[coccyx  1 

("sternum  or  breast  bone  1 

|  ribs  24 

[  innominate  or  hip  bone  2 

|  clavicle  or  collar  bone  2 
|  scapula  or  shoulder  blade  2 
humerus  2 
f  radius  2 
{ulna  2 

carpal  16 
metacarpal  10 
phalanges  28 

{femur  or  thigh  bone  2 
tibia  or  shin  bone  2 
fibula  2 
patella  or  knee  pan  2 
tarsal  14 
metatarsal  10 
phalanges  28 


Kinds  of  Bones.  —  In  respect  to  shape,  there  are  five 
groups  of  bones  :  the  flat  bones,  such  as  those  of  the  cra- 
nium, the  shoulder  blade,  and  the  ribs ;  the  irregular  bones, 
including  the  ethmoid,  sphenoid,  and  vertebrae ;  the  short 


DAT.  PHYS.  13 


194 


THE   OSSEOUS   SYSTEM,   OR   BONES 


bones,  represented  by  those  in  the 
wrist  and  ankle;  the  long  bones, 
composed  of  a  hollow  shaft  and 
two  enlarged  ends,  such  as  those 
in  the  leg  and  arm ;  and  the 
sesamoid  bones,  like  the  patella, 
formed  in  the  region  of  joints  by 
friction  or  pressure.  The  number 
of  sesamoid  bones  increases  in 
accordance  with  age  and  the 
amount  of  physical  labor  done. 

Composition  of  Bone.  —  Bone  is 
composed  of  animal  and  mineral 
matter,  .the  latter  of  which  is 
chiefly  phosphate  and  carbonate 
of  lime.  By  placing  a  slender 
bone  from  any  animal  in  water 
containing  one  tenth  part  of  nitric 
acid  or  hydrochloric  acid,  the 
mineral  matter 
will  be  so  com- 
pletely dissolved  out  in  four  days 

that   the  bone   will   be   as   limber  as 

cartilage.      From    another    bone    the 

animal    matter   may   be   removed    by 

burning  it  a  half  hoar  in  the   stove, 

after  which  it  will  be  so  brittle  as  to 

crumble   into   dust  at    the    touch   of 

the  fingers. 

The    Parts   of   a   Bone.  —  All    the 

bones  are  covered  with  a  tough  con- 


FIG.  122.  —  A,  leg.  B,  arm. 
a,  tarsus;  c,  carpus;  cl, 
clavicle ;  m,  metacarpus : 
mt,  metatarsus;  p,  pha- 
langes ;  s,  scapula. 


FIG.  123.  — Rib  from 
which  the  mineral 
matter  has  heen  dis- 
solved by  acid. 


THE   PARTS   OF   A   BONE 


195 


nective-tissue  membrane,  named 
the  periosteum.  This  serves  for 
the  attachment  of  tendons  and 
muscles,  and  has  the  power  of 
renewing  any  portion  of  bone 
removed  by  the  surgeon  on  ac- 
count of  disease  or  accident. 

The  bony  tissue  itself  is  of 
two  kinds.  One  is  called  com- 
pact or  hard  bone,  and  the  other 
is  the  cancellous  or  spongy  lone. 
The  outer  part  of  the  skeleton 
is  made  of  compact  bone,  but 
it  forms  a  very  thin  layer, 
except  in  the  long  bones,  where 


FIG.  125.  —  Thin  slice  of  bone  half  the  size 
of  the  cross  section  of  a  pin.  The  two 
•white  circles  are  Haversian  canals,  and  the 
black  spots  are  lacunae  or  spaces  for  the 
living  bone  cells.  Photographed  through 
the  microscope. 


FIG.  124.  —  Upper  part  of  the 
femur  cut  open  to  show 
c,  compact  tissue;  en, 
cancellous  tissue;  I,  med- 
ullary canal. 

it  makes  nearly  all  of 
the  shaft,  or  middle 
part,  between  the  en- 
larged extremities. 
The  cancellous  tissue 
is  abundant  in  the 
interior  of  all  bones,, 
except  the  long-  ones,, 
where  it  is  chiefly 
present  only  at  the 
ends.  The  shaft  con- 
tains a  cavity  known 
as  the  medullary 
canal.  This  is  oc- 
cupied by  the  medulla, 
or  white  marrow.  It 
is  largely  made  of  fat. 


196 


THE   OSSEOUS   SYSTEM,    OR   BONES 


The  Structure  of  Bone.  —  If  a  slice  is  sawed  from  a 
bone  and  ground  very  thin  on  a  whetstone,  it  will  pre- 
sent under  the  microscope  many  circular  openings,  called 
Haversian  canals^  which  in  life  contained  blood  vessels 

and  nerves.  The 
numerous  small 
holes  in  the  sur- 
face of  a  bone  are 
for  the  entrance  of 
vessels  and  nerves 
to  the  Haversian 
canals.  Irregular 
oval  spaces,  the 
lacunae,  with  fine 
radiating  channels 
are  arranged  in 
circles  about  the 
Haversian  canals. 
Each  lacuna  in  live 
bone  is  filled  with 
a  cell,  which  is 
nourished  by  the 
blood  escaping  from 
the  vessels  in  the 
Haversian  canals 


(Fig.  125). 


FIG.  rj<>.  —  X-ray  view  of  the  hand  of  a  child  five 
years  of  age.  Only  three  of  the  eight  bones  of 
the  wrist  are  formed  and  many  of  the  end  pieces 
of  the  other  bones  are  not  united  to  the  shafts. 
Photographed  by  Dr.  W.  W.  Seibert. 

The  Development 

of  Bone.  —  Most  of  the  bones,  except  those  forming 
the  top  and  sides  of  the  skull,  are  developed  from 
cartilage.  This  is  a  tough  white  substance,  commonly 
called  gristle.  It  may  be  easily  bent  and  pressed  out 


THE   DEVELOPMENT    OP    BONE 


197 


of  shape.  In  the  young  child,  since  much  of  the 
cartilage  is  not  yet  changed  into  bone,  the  legs  may  be- 
come bent  or  bowed  if  it  is  allowed  to  stand  too  much. 
In  older  children,  during  the  first  years  of  school,  the 
thigh  bones  may  be 
given  a  permanent 
curve  backward  if 
the  seat  is  so  high 
that  the  feet  cannot 
touch  the  floor. 

The  ends  of  most 
of  the  long  bones 
are  joined  to  the 
shaft  by  cartilage 
only  until  the  six- 
teenth year,  or  even 
later.  At  birth  the 
skull  is  quite  in- 
complete on  the 
sides  and  top,  so 
that  between  the 
bones  are  six  spaces 
where  only  mem- 

,  .  FIG.  127.  —  X-ray  view  of  the  hand  of  an  ndult. 

brane  separates  the  Photographed  by  Dr.  W.  W.  Seibert. 

brain  from  the  skin. 

These  are  not  completely  closed  by  bone  until  near  the 
end  of  the  second  year,  so  that  a  slight  stroke  on  the 
head  of  a  young  child  might  prove  very  serious.  Unless 
the  clothing  about  the  waist  of  children  is  worn  loose, 
the  bones  of  the  thorax  may  be  pressed  in  so  as  to  pre- 
vent the  internal  organs  from  doing  their  work. 


198 


THE    OSSEOUS    SYSTEM,    OR    BONES 


Broken  Bones.  —  A  break  in  a  bone  is  called  a,  fracture. 
As  the  bones  of  children  bend  easily,  they  are  seldom 
broken  off  completely,  but  are  cracked  somewhat  like  a 
tough  stick  when  bent.  This  is  known  as  a  green-stick 
fracture.  When  the  bone  of  an' older  person  is  broken, 

the  ends  usually  separate  some- 
what, owing  to  the  pull  of  the 
muscles.  In  order  to  set  the 
bone  properly,  the  two  ends 
must  be  brought  together  and 
held  firmly  in  place  by  a  thin 
board  or  sheet  of  metal  band- 
aged on  the  limb.  No  one 
but  a  good  physician  is  capable 
of  setting  a  broken  bone  success- 
fully. However,  if  a  person 
with  a  fracture  must  be  moved 
from  the  place  of  accident,  it 
is  wise  to  hold  the  broken  bones 
in  place  by  binding  firmly  on 
either  side  of  the  fracture,  en- 
veloped in  clean  cloth  or  cotton, 
a  narrow  board  or  flat  stick. 
When  the  parts  of  the  bone 

broken  render  little  injury  to  the  flesh,  the  fracture 
is  said  to  be  simple.  A  compound  fracture  is  one  in 
which  the  ends  of  the  bone  protrude  through  the 
skin.  In  young  persons  broken  bones  usually  knit 
together  in  three  or  four  weeks,  but  in  persons  over 
sixty  years  of  age  healing  sometimes  requires  several 
months. 


FIG.  128.  —  Femurs  which  were 
fractured.  The  one  on  the 
right  was  not  properly  cared 
for,  and  the  ends  have  pushed 
over  each  other. 


DISEASE   OF   BONES 


199 


FIG.  129.— Temporary  bandage 
for  a  broken  bone  until  the 
surgeon  arrives,  n  is  a  piece 
of  board,  and  a  similar  piece 
is  on  the  back  of  the  arm. 


Disease  of  Bones.  —  The  com- 
monest disease  of  bones  is 
tuberculosis,  caused  by  the 
growth  of  a  minute  plant,  the 
consumption  germ.  White 
swelling,  hunchback,  curvature 
of  the  spine  and  hipjoint  dis- 
ease may  result  from  bone 
tuberculosis.  It  is  the  most 
frequent  in  children  fed  on  the 
raw  milk  of  diseased  cows  or 
living  in  daily  contact  with  a 
person  suffering  from  consump- 
tion. It  has  lately  been  found 
that  many  cases  can  be  cured  by 
good  food  and  fresh  air,  especially  along  the  seashore. 

The  first  of  the  sea- 
shore sanatoria  needed 
to  treat  the  60,000 
children  in  this  country 
suffering  from  bone  tu- 
berculosis was  estab- 
lished in  1906. 

A  felon  is  an  inflam- 
mation of  the  perios- 
teum, caused  by  bacteria 
finding  entrance  and 
developing.  Rickets 
occur  in  children  not 
sufficiently  nourished 
to  permit  the  deposit 


FIG.  130.— Hip  bone  and  end  of  the  thigh, 
to  show  the  character  of  a  joint. 


200 


THE   OSSEOUS   SYSTEM,    OR    BONES 


of  enough  mineral   matter  in  the  bones  to  render  them 
hard. 

The  Joints.  —  The  juncture  of  two  or  more  bones  is  a 
joint,  or  articulation.     The  two  general  classes  of  joints 
are   the   movable  and  immovable.     The  immovable  joints 
occur   between   the   bones   of    the 
skull,  and  are  often  called  sutures. 
The  two  important  kinds  of  mov- 
able joints  are  the  ball  and  socket 
joint,  like  that  at  the  shoulder  and 
hip,  and  the  hinge  joint,  as  seen  at 
the  knee  and  elbow. 

In  the  movable  joints  the  adja- 
cent ends  of  the  bones  are  covered 
with  a  thin  pad  of  cartilage,  and 
several  tough  inelastic  bands  of 
white  fibrous  connective  tissue, 
called  ligaments,  hold  the  bones  in 
place,  and  form  about  the  space 
between  the  ends  of  the  bones  a 
capsule.  This  is  lined  with  a  deli- 
cate membrane,  called  the  synovial 
membrane  (Fig.  131).  It  secretes 
from  the  blood  a  thick  fluid,  the  synovia,  similar  to  the 
white  of  egg.  This  glairy  fluid  is  necessary  to  keep 
the  joint  moist. 

Strain  and  Sprain.  —  By  bending  a  joint  too  far  or  push- 
ing the  end  of  a  bone  to  one  side,  the  ligaments  may  be 
stretched  and  slightly  torn,  resulting  in  swelling  and  ten- 
derness, called  a  strain.  A  severe  strain  is  a  sprain.  The 
best  immediate  treatment  is  to  immerse  the  injured  part 


FIG.  131. — Diagram  of 
a  section  through  a 
joint.  The  bones  are 
shown  more  separated 
and  the  cartilage 
thicker  than  in  nature, 
c,  cartilage;  ?,  liga- 
ment; s,  synovial 
membrane. 


NARCOTICS   AND   BONE   GROWTH  201 

in  hot  water  or  wrap  it  in  cloths  wrung  out  of  hot  water, 
and  change  them  every  few  minutes.  At  the  end  of  a 
half  hour  the  joint  should  be  massaged  by  rubbing  it 
t«)\\ard  the  body  in  order  to  move  the  collected  lymph 
away  to  the  veins.  Unless  the  ligaments  are  torn,  com- 
plete rest  is  not  so  helpful  as  careful  exercise  and  frequent 
massaging. 

Dislocation  of  Bones.  —  When  at  a  joint  the  end  of  one 
of  the  bones  is  forced  backward,  forward,  or  to  one  side 
of  the  other  bone  so  far  that  it  does  not  slip  back  into 
place,  it  is  said  to  be  dislocated.  The  ligaments  may  be 
torn  or  greatly  stretched.  The  services  of  a  physician 
are  usually  necessary  to  remedy  the  difficulty.  The  bones 
at  the  knee  and  shoulder  joints  are  the  ones  most  fre- 
quently dislocated,  and  fortunately  are  often  quite  easily 
put  in  place  by  a  strong  pull  on  the  limbs. 

Narcotics  and  Bone  Growth. — The  bones  derive  material 
for  their  development  from  the  food  eaten.  When  the 
food  has  reached  the  stomach  and  intestine,  it  must  be 
properly  digested  before  it  can  be  absorbed  and  carried 
through  the  body  to  build  up  the  bones.  Alcoholic  drinks, 
soothing  sirups  for  children,  and  tobacco  have  a  tendency 
to  diminish  digestion.  They,  therefore,  in  some  degree 
prevent  the  proper  food  supply  from  reaching  the  bones. 

When  the  bone-building  cells  of  the  body  are  ever  so 
slightly  stupefied  by  narcotics  of  any  kind,  they  fail  to 
take  from  the  blood  and  use  what  is  needed  to  make  sound 
bones.  Evidence  is  gradually  accumulating  which  indi- 
cates that  the  stunted  frames  of  some  children  in  alcoholic 
families  are  due  in  part  at  least  to  the  effects  of  alcohol. 
On  this  account,  beer  should  never  be  given  to  children. 


202  THE  OSSEOUS   SYSTEM,    OR   BONES 

Questions 

1.  Of  what  use  are  the  bones  ?  2.  What  are  the  three  parts  of  the 
skeleton?  3.  Point  out  on  your  head  the  two  parts  of  the  skull. 
4.  Point  out  the  location  of  five  bones  of  the  cranium.  5.  Point  out 
five  bones  of  the  face.  6.  Of  what  is  the  vertebral  column  formed? 
7.  Give  the  number  of  ribs.  8.  Name  five  bones  in  your  upper  ex- 
tremity. 9.  How  many  phalanges  in  each  finger?  10.  Wherein  does 
the  arrangement  of  the  bones  of  the  leg  differ  from  that  in  the  arm  ? 
11.  Give  the  composition  of  bone.  12.  State  five  facts  concerning  the 
parts  of  a  bone.  13.  From  what  are  bones  developed?  14.  Explain 
how  broken  bones  should  be  cared  for.  15.  Why  should  a  heavy  strain 
not  be  put  upon  the  bones  of  the  young  ?  16.  Point  out  on  your  body 
and  name  three  kinds  of  joints.  17.  Describe  the  parts  of  a  joint. 
18.  How  should  a  sprain  be  treated?  19.  What  is  meant  by  the  dis- 
location of  a  bone?  20.  How  does  alcohol  affect  bone  growth? 

Suggestions  for  the  Teacher 

1.  Ask  a  pupil  to  procure  from  a  butcher  a  bone  about  a  foot  long, 
sawed  lengthwise.     Observe  in  class  the  periosteum,  the  red  marrow, 
the  white  marrow,  and  the  two  kinds  of  bony  tissue. 

2.  Secure  from  the  butcher  a  joint.     Look  for  the  ligaments  unit- 
ing the  bones,  by  tearing  away  all  muscle  and  fat.    Cut  open  the  joint 
and  note  the  few  drops  of  sticky  synovial  fluid  and  the  transparent 
synovial  membrane  as  thin  as  tissue  paper  on  the  inside  of  the  liga- 
ments. 

3.  Ask  one  pupil  to  show  on  another's  arm  how  a  fracture  is  to  be 
treated  when  the  patient  must  be  moved  before  the  arrival  of  the 
surgeon. 


XVIII.     THE   MUSCULAR   SYSTEM 


The  Parts.  —  The  muscular 
system,  like  the  other  systems, 
is  composed  of  parts  or  organs, 
each  of  which  is  a  muscle. 
The  muscle  is  the  lean  meat 
of  the  body  and  is  made  of  a 
tissue  which  has  the  property 
of  contracting  or  becoming 
shorter  in  length  while  its 
thickness  increases.  This 
change  in  shape  is  produced 
by  a  peculiar  chemical  action, 
resulting  from  a  stimulus  pass- 
ing from  the  nervous  system 
to  the  muscle.  We  can  send 
this  stimulus  to  most  parts  of 
the  muscular  system  at  will, 
and  the  muscles  thus  made  to 
act  are  named  voluntary.  We 
cannot,  however,  control  by 
our  will  the  muscles  helping 
to  form  the  walls  of  the  blood 
vessels,  stomach,  and  intes- 
tines, and  on  this  account  they 
are  known  as  involuntary 
muscles. 

203 


FIG.  132.  —  Muscles  and  tendons 
on  the  back  of  the  arm. 


204 


THE   MUSCULAR   SYSTEM 


FIG.  133.  —  A  tiny  bit  of  involuntary  mus- 
cle magnified  to  show  the  cells,  n, 
nucleus. 


The  Involuntary  Mus- 
cles. —  They  are  often 
called  plain  or  unstri- 
ated  muscles,  because  of 
the  smooth  appearance 
of  the  cells  seen  under 
the  microscope.  The 
muscles  in  the  skin 
and  in  nearly  all  of 
the  tubes  of  the  body 
are  involuntary.  The 
movements  of  the 
stomach  and  intestines 
and  the  contraction  of 

the   blood  vessels   helping   to   regulate    the   heat  of   the 

body   are   produced   by  the   involuntary  muscles.       The 

will  has  no   control 

over  them,  but  when 

food  comes  into  the 

intestines,  it   affects 

the  endings  of  nerves 

there    which     are 

aroused     to    action, 

and    the   stimulus 

goes  to  the  cells  of 

the  spinal  cord,  caus- 
ing them  to  send 

out    a    stimulus    to 

make  the  muscles  of 

the    intestines     act.     FlG" 13*'  ~  A  bit  °f  ;oluf  T  muscle  as  thu-k 

as  a  hair  magnified  to  show  the  stnations  of 
Cold,  acting    on    the          fibers.  Photographed  through  the  microscope. 


THE   MATURE  OF   A   VOLUNTARY  MUSCLE 


205 


nerves,  causes  the  muscles  in  the  skin  to  contract  and 
produce  the  rough  goose  flesh  often  seen  on  the  bare 
arm  after  a  cold  bath. 

The  heart  is  made  of  involuntary  muscle,  but  the  cells, 
being  short,  thick,  and  striped,  are  quite  different  from 
those  of   the  other  in- 
voluntary muscles. 

The  Nature  of  a  Vol- 
untary Muscle.  — What 
is  -usually  spoken  of 
as  flesh  or  lean  meat 
is  composed  of  the 
voluntary  or  striated 
muscles.  There  are 
about  400  of  them 
in  the  human  body. 
They  are  of  a  reddish 
pink  color,  and  each 
one  is  surrounded  by 
a  transparent  sheath 

which   is  joined   to   the     FlG-  135.  — Action  of   biceps  muscle.     6, 
,.  extended;    a,    contracted;    h,  humerus; 

adjacent  muscles.  8j  scapuia. 

The  important  ele- 
ments of  a  muscle  are  the  fibers,  which  have  the  shape  of 
rods.  They  vary  in  length  from  les^j  than  a  quarter 
of  an  inch  to  over  two  inches,  and  are  so  slender  that 
a  dozen  of  them  together  would  not  be  as  thick  as 
a  hair.  The  fibers  are  easily  seen  by  tearing  into  bits, 
in  a  drop  of  water  on  a  glass  slide,  a  small  piece  of  beef 
or  other  muscle,  and  examining  it  with  the  microscope. 
Between  the  fibers  are  numerous  arteries,  capillaries,  and 


206 


THE  MUSCULAR   SYSTEM 


veins  for  the  purpose  of  supplying  oxy 
gen  and  food,  and  taking  away  the 
waste  resulting  from  the  life  processes. 
The  Use  of  Muscles.  —  The  chief  func- 
tion of  the  muscles  is  to  produce  motion 
in  any  part  of  the  body.  Usually  the 
ends  of  a  muscle  are  attached  to  dif- 
ferent bones,  so  that  when  it  contracts 
one  of  the  bones  must  move.  Several 
of  the  muscles  attached 
to  the  bones  of  the 
fingers  have  their 
other  ends  fixed  on 
the  humerus  (Fig. 
136).  The  muscles 
pulling  on  the  femur 
have  an  attachment  on 
the  hip  bone.  A  mus- 
cle is  able  to  contract 
nearly  one  fourth  of 
its  length. 
The  contracting  muscles  serve  an 

important   purpose    in.    pressing    upon 

the  veins  and  lymphatics  so  as  to  move 

their  contents,  which  must  always  go 

toward   the    heart    on   account   of   the 

valves  in  the  vessels.      Other  uses  for      FIG.  137.— Muscles 

the   muscles   are   to    protect   the  blood        on  the  front  of  the 

1  thigh,    v,  a,  and  i 

vessels  and  nerves  from  injury  and  add        are  the  three  parts 
beauty  and  symmetry  to  the  form   of        of  the  quadriceps 

J  extensor.     /,   hip 

the  body.  bone. 


FIG.  136.  — Flexor 
muscles  on  the 
front  of  the  fore- 
arm with  ten- 
dons at  the  wrist. 


THE   ARRANGEMENT    OF   THE   MUSCLES 


207 


The  Arrangement  of  the  Muscles.  —  In  some  regions  of 
the  body  only  a  single  layer  of  muscles  covers  the  bones, 
while  in  other  parts  as  many  as  three  layers  occur. 
Usually  a  muscle  is  attached  to  two  different  bones,  but 
one  end  may  be 
fastened  to  the  skin 
or  another  muscle, 
and  in  some  cases 
one  end  of  the  mus- 
cle is  divided  into 
several  parts.  The 
end  of  the  muscle 
fixed  on  the  bone 
which  it  moves  is 
called  the  insertion, 
while  the  other  end 
is  the  origin.  The 
masseter,  or  chewing 
muscle,  has  its  origin 
on  the  cheek  bone 
and  its  insertion  on 
the  mandible. 

In  some  cases  the 
muscle  fibers  join 
directly  to  the  peri- 
osteum of  the  bone,  but  in  others  a  tough  white  cord, 
called  a  tendon,  apparently  continuous  with  the  muscle 
fibers,  occurs  at  either  or  both  ends  of  the  muscle  to  con- 
nect it  to  the  bone.  The  largest  is  the  Achilles1  tendon, 
which  feels  like  a  hard  cord  a  half  inch  thick  just  above 
the  heel.  Several  tendons  may  be  felt  in  the  wrist. 


FIG.  138.  —  Some  of  the  muscles  used  in  breath- 
ing, a,  muscles  under  the  scapula;  e,  car- 
tilage part  of  the  rib;  h,  humerus;  ra, 
muscles  pulling  on  the  ribs  when  the  arms 
are  thrown  backward ;  n,  intercostal  muscles ; 
r,  rib ;  «,  sternum. 


208 


THE   MUSCULAR   SYSTEM 


Kinds  of  Muscles.  —  In  reference  to  the  action  effected, 
the  muscles  are  divided  into  five  groups  :  1.  the  flexors 
are  those  which  bend  a  limb;  they  occupy  the  palm  side 
of  the  hand  and  arm,  and  the  back  of  the  leg  (Fig.  136)  ; 
2.  the  extensors  straighten  a  lirnb,  and  therefore  lie  on 

the  side  of  the  limbs 
opposite  to  the  flexors 
(Fig.  132)  ;  3.  the  ab- 
ductors pull  a  limb  or  a 
part  of  a  limb  outwards, 
as  when  the  arms  are 
stretched  outward  on 
either  side  ;  4.  the  ad- 
ductors oppose  the  ab- 
ductors, as  seen  in  the 
action  of  the  pectoral 
muscles  of  the  chest 
when  drawing  the  arm 
across  the  breast ;  5. 
the  sphincters  are  ring- 
like  muscles  and  sur- 
round openings,  such  as 
the  mouth  and  the  eye. 
The  score  of  muscles 
controlling  the  eyes, 

mouth,  and  other  features  of  the  face  are  the  muscles  of 
expression,  and  on  their  action  depends  largely  whether  one 
has  a  pleasing  or  unattractive  countenance.  In  one  who  is 
accustomed  to  pout,  frown,  or  cry  about  every  trifle,  the 
muscles  become  so  trained  to  pulling  down  the  corners 
of  the  mouth,  pushing  out  the  lips  and  wrinkling  the 


FIG.  139.  —  Portrait  showing  how  the 
shoulders  are  rounded  and  the  chest  com- 
pressed, thus  inviting  tuberculosis. 


EXERCISE 


209 


r^m 

mm 

FIG.  140.  —  Ungraceful 
attitude  preventing  the 
full  expansion  of  the 
lungs. 


forehead  that  the  face  can  never  have  a  pleasant  aspect. 
Persons  called  homely  are  often  the  most  delightful  com- 
panions because  of  their  pleasant  looks  and  kind  words, 

helping  every  one   to  wear  a  smile. ( 

A  charming  expression  can  be  culti- 
vated by  any  one. 

The  diaphragm  and  most  of  the 
other  muscles  attached  to  the  ribs  are 
concerned  in  respiration,  because  it 
is  only  when  the  diaphragm  is  pulled 
down  or  the  ribs  drawn  up  that  the 
pressure  is  decreased  in  the  chest  so 
as  to  cause  the  air  to  flow  into  the 
lungs.  The  muscles  of  locomotion 
are  those  controlling  the  legs. 

Exercise.  —  No  one  can  remain  in 
good  health  very  long  without  tak- 
ing some  form  of  exercise.  If  one's 
regular  work  does  not  compel  him  to 
move  nearly  all  of  the  muscles  of  the 
body,  he  must  devise  some  plan  that 
will  bring  the  muscles  into  action.  Neither  a  gymnasium 
nor  expensive  apparatus  is  necessary  for  the  best  form  of 
exercise,  though  they  are  great  aids  in  influencing  the 
young  in  the  right  direction.  The  playing  of  some  game 
in  the  open  air,  such  as  paper  chase,  and  swimming,  row- 
ing, climbing  trees,  botanizing,  and  studying  nature,  are 
splendid  ways  of  bringing  all  muscles  into  play.  A 
tennis  court  well  used  will  save  doctor's  bills. 

Round  shoulders,  narrow  chests,  diseased  lungs,  slug- 
gish liver,  and  constipation  may  be  prevented  or  remedied 

DAY.  FHY3.  14 


210 


THE   MUSCULAR    SYSTEM 


by  exercise  regularly  taken.  A  good  position  in  stand- 
ing and  sitting  and  a  graceful  carriage  in  walking  should 
be  practiced  both  for  health  and  appearance.  The  droop- 
ing of  the  shoulders  and  the  projecting  of  the  chin  and 
abdomen  are  common  faults  in  young  people.  Exercise 
and  fresh  air  have  cured  ten  times 
more  cases  of  consumption  than  all 
medicines  combined.  It  is  not  over- 
study  that  breaks  one  down  and 
causes  nervous  prostration,  but  lack 
of  exercise  and  fresh  air.  One  of 
the  most  important  parts  of  the 
treatment  for  the  sick  in  sanatoria 
consists  of  certain  forms  of  exercise. 

Massaging.  —  This  process  consists 
in  pinching,  pressing,  squeezing,  and 
kneading  the  muscles,  skin,  and  in- 
ternal organs  in  such  a  way  as  to 
cause  the  lymph  with  its  collected 
impurities  to  pass  away  and  the 
organs  to  become  more  active.  A 
massage  has  somewhat  the  same 
effect  as  exercise.  The  circulation 

is  stimulated,  and  the  tissues  purified.  It  likewise  has 
a  very  beneficial  effect  on  the  nervous  system.  To 
massage  most  efficiently,  one  should  have  special  train- 
ing from  an  expert,  but  almost  any  one,  with  a  little 
practice,  can  accomplish  much  in  relieving  pain  and 
sleeplessness  by  rubbing  and  kneading  the  muscles  so 
as  to  force  the  lymph  and  impure  blood  toward  the 
heart. 


FIG.  141.  —  A  graceful 
and  restful  position 
conducive  to  health. 


HOW   ALCOHOL   AFFECTS  THE   MUSCLES  211 

Tobacco  and  the  Muscles.  —  Nicotine  causes  the  invol- 
untary muscles  of  the  small  blood  vessels  to  contract,  and 
thus  shut  off  some  of  the  nourishment  intended  for  the 
growth  of  the  muscles.  The  habitual  use  of  tobacco 
affects  the  growth  of  the  young  in  a  very  marked  degree. 
At  Yale  University  during  four  years  the  non-users  of 
tobacco  gained  24  per  cent  more  in  height  and  26.7  per 
cent  more  in  the  girth  of  the  chest  than  the  habitual 
users  of  tobacco.  Dr.  Seaver,  of  New  Haven,  found,  on 
examining  a  large  number  of  young  men,  that  the  tobacco 
users  at  18  years  of  age  were  not  so  large  and  well  devel- 
oped as  the  non-users  only  17  years  old.  That  the  use 
of  tobacco  dwarfs  the  young  there  is  no  doubt. 

For  perfect  control  of  the  muscles  there  must  be  a  per- 
fect nervous  system.  The  nerve  cells  of  the  young  are 
very  delicate  structures  and  cannot  perform  their  duties 
accurately  when  dulled  by  such  a  poison  as  nicotine. 

Professor  Drawing,  of  the  Naval  Academy,  says  that 
smokers  are  not  able  to  control  their  muscles  accurately, 
and  he  can  discover  the  tobacco  users  by  their  inability  to 
draw  a  straight  line  or  hold  the  hand  perfectly  still. 

How  Alcohol  affects  the  Muscles. —  Alcohol  may  stimu- 
late the  muscles  for  a  few  minutes  somewhat  in  the  same 
way  that  a  whip  urges  forward  a  horse,  but  recent  experi- 
ments all  agree  in  showing  that  the  daily  amount  of  work 
accomplished  by  men  using  alcohol  is  always  less  than  that 
done  by  the  total  abstainers.  On  this  account  no  athlete 
while  in  training  makes  use  of  whisky,  wine,  or  beer. 
Soldiers  on  forced  marches  are  found  to  make  better  prog- 
ress when  denied  the  use  of  alcohol  and  given  beef  tea. 
Brigadier  General  A.  W.  Greely  says  that  it  should  be 


212  THE  MUSCULAR   SYSTEM 

strongly  urged  that  no  alcoholic  drink  be  used  by  soldiers 
undergoing  great  physical  hardship  and  frequent  exhaust- 
ing labor. 

Scientists,  as  a  result  of  recent  investigations,  are  unani- 
mous in  the  opinion  that  a  man  can  run  faster,  shoot 
straighter,  and  lift  more  without  the  use  of  alcohol  than 
he  can  by  using  it  in  either  small  or  large  quantities. 
Sir  Frederick  Treves,  in  speaking  of  his  experiences  in  the 
Boer  War,  says:  "It  is  also  curious  that  troops  cannot 
work  or  march  on  alcohol.  I  was,  as  you  know,  with  the 
relief  column  that  moved  on  to  Ladysmith,  and,  of  course, 
it  was  an  extremely  trying  time  by  reason  of  the  hot 
weather.  In  that  enormous  column  of  30,000,  the  first 
who  dropped  out  were  not  the  tall  men,  or  the  short  men, 
or  the  big  men,  or  the  little  men — they  were  the  drinkers, 
and  they  dropped  out  as  clearly  as  if  they  had  been 
labeled  with  a  big  letter  on  their  backs."  The  excessive 
use  of  beer  tends  to  change  the  muscle  cells  of  the  heart 
into  fat,  so  that  the  organ  finall}r  becomes  weakened 
sufficiently  to  refuse  to  act,  and  sudden  death  results. 

Questions 

1.  What  special  property  is  possessed  by  muscle?  2.  Where  are 
involuntary  muscles  found  ?  3.  How  are  muscles  made  to  act  ? 
4.  Give  two  features  of  involuntary  muscles.  5.  Explain  the  nature 
•of  voluntary  muscle.  6.  Of  what  use  are  muscles?  7.  Explain  the 
meaning  of  origin,  insertion,  and  tendon.  8.  Point  out  on  your  body 
and  name  four  kinds  of  muscles.  9.  Why  does  the  expression  of  the 
face  depend  upon  the  muscles  ?  10.  Explain  how  and  why  the  mus- 
cles should  be  exercised.  11.  Describe  massaging  and  its  effects. 
12.  How  does  tobacco  affect  the  muscles?  13.  Give  facts  showing 
that  tobacco  is  injurious  to  muscular  development.  14.  How  does 
alcohol  affect  the  muscles?  15.  How  many  muscles  in  the  body  ? 


SUGGESTIONS   FOR   THE   TEACHER  213 

Suggestions  for  the  Teacher 

1.  The  leg  of  a  frog  or  chicken  in  which  the  muscles  have  been 
loosened  from  each  other  by  cutting  the  connective  tissue  uniting  them 
may  be  prepared  by  the  teacher  or  some  of  the  older  pupils  and  kept 
permanently  for  demonstration.     Ask  the  pupils  to  note  the  difference 
between  the  muscle  and  tendon,  and  how  the  muscle  or  tendon  is  joined 
to  the  bone. 

2.  Observe  through  the  skin  the  three  tendons  on  the  front  of  the 
wrist,  and  by  working  the  fingers  and  thumb  determine  where  the 
tendons  are  inserted. 

3.  Require  the  class  to  perform  some  simple  gymnastic  exercises 
helpful  in  preventing  round   shoulders   and  flat   chests.      Call  the 
attention  of  the  pupils   to   the  graceful  positions  in  walking   and 
standing. 

4.  When  possible,  it  will  prove  of  great  interest  and  value  to  have 
a  trained  nurse  or  physician  show  the  pupils   how  to  massage  and 
produce  most  helpful  results  in  such  simple  ailments  as  a  slightly 
sprained  wrist  or  a  stiff  neck. 


PIG.  142.— The  nervous  system,    c,  cerebellum;   the  large  nerve  of  thb 
leg  is  the  sciatic ;  the  white  line  down  the  back  is  the  spinal  cord. 


XIX.     HOW   THE   NERVOUS   SYSTEM   IS 
CONSTRUCTED 


Parts.  —  The  nervous  apparatus  of  the  body  may  be 
considered  in  three  parts  :  the  central  nervous  system,  in- 
cluding the  brain  and  spinal  cord  ;  the  nerves,  extending 
from  the  brain  and 
cord  to  all  parts  of 
the  body  ;  and  the 
sympathetic  system, 
composed  of  bunches 
of  cells,  chiefly  in 
the  body  cavity, 
with  their  nerves 
supplying  the 
glands,  and  the  in- 
voluntary muscle  in 
the  entire  body. 
The  nervous  system 
bears  the  same  re- 
lation to  the  organs 
of  the  body  as  the 
manager  of  a  large  establishment,  with  the  telephone  wires 
leading  to  all  departments,  does  to  the  workmen.  The 
brain  and  spinal  cord  direct  the  other  organs  as  to  the 
amount  of  work  to  be  done,  and  the  time  tc  do  it. 

The  Brain. — The  brain  fills  loosely  the  cavity  of  the 
skull,  in  which  it  is  securely  fastened  and  protected  by 

215 


FIG.  143. —The  braiu  in  the  skull,  with  its 
upper  half  removed .  Membranes  of  the  brain 
are  taken  off  to  show  the  convolutions  ap- 
pearing as  folds  separated  by  the  sulci. 


216 


HOW   THE   NERVOUS   SYSTEM    IS    CONSTRUCTED 


three  membranes,  named  the  dura  mater,  arachnoid,  and 
pia  mater.  The  dura  mater  is  tough  and  sticks  closely  to 
the  skull,  while  the  other  two  are  very  delicate.  The  pia 
mater,  carrying  blood  vessels,  dips  down  into  all  crevices 
of  the  brain.  These  crevices  are  known  as  sulci,  arid  the 
larger  ones,  being  an  inch  or  more  deep,  are  named  fissures. 

The  irregular  convex  portion 
of  matter  between  any  two 
sulci  is  a  convolution  (Fig. 
144). 

The  brain  is  in  communi- 
cation with  all  parts  of  the 
body  by  means  of  white 
cords,  the  nerves.  Some  of 
them  branch  in  several 
places  from  the  lower  side 
of  the  brain,  and  extend  to 
the  head  and  neck,  while 
others  at  the  back  part  of 

the  brain  unite  into  a  large  bundle,  called  the  spinal 
cord.  This  extends  down  the  back  within  the  inch- 
wide  canal  of  the  vertebrae,  and  gives  off  between  the 
bones  of  the  spinal  column  branches  leading  to  the  arms, 
trunk,  and  legs. 

The  Parts  of  the  Brain.  —  The  three  parts  of  the  brain 
most  clearly  marked  off  on  the  surface  are  the  medulla 
ollongata,  or  medulla,  the  cerebellum,  or  little  brain,  and  the 
cerebrum,  orforebrain. 

The  medulla  is  the  stem  or  bulb  joining  the  higher  parts 
of  the  brain  with  the  spinal  cord.  With  it  are  connected 
eight  pairs  of  nerves  distributed  chiefly  to  the  head. 


FIG.  144. —  The  brain  from  the  side. 
ce,  cerebellum ;  c,  spinal  cord ;  m, 
medulla  oblongata;  p,  pons  Va- 
rolii ;  s,  fissure  of  Sylvius  in  the 
cerebrum. 


THE   CEREBRUM 


217 


The  cerebellum,  almost  as  large  as  one's  fist,  lies  above 
and  back  of  the  medulla.     Its  surface  is  marked  by  deep 
cuts  or  sulci,  forming  plates  of  matter.     The  cerebellum 
is  united  to  the  other 
parts  of  the  brain  and 
the     spinal     cord     by 
several  bands  of  nerve 
fibers.       The     middle 
part   of   one   of    these 
is  the  pans  Varolii,  ap- 
pearing as  a  flat  band 
on   the   lower   side   of 
the  brain  just  in  front 
of  the  medulla. 

The  cerebrum  is  di- 
vided incompletely  by 
the  great  longitudinal 
fissure  into  two  equal 
parts,  called  hemi- 
spheres. They  are 
connected  with  each 
other  at  the  base  and 
also  with  the  other 
parts  of  the  brain  and 
cord  by  means  of  nerve 
fibers  (Fig.  146). 

The  Cerebrum.  —  Each  hemisphere  is  divided  into  five 
indistinct  parts,  called  lobes,  and  named  according  to  the 
bones  of  the  skull  nearest  them. 

The  two  chief  fissures,  in  addition  to  the  great  longi- 
tudinal one  between  the  hemispheres,  are  the  fissure 


FIG.  145.  —  View  of  the  brain  from  beneath, 
showing  a  dozen  pairs  of  cranial  nerves 
cut  off.  oi,  olfactory  tract,  or  roots  of  the 
nerve  of  smell,  bearing  at  the  end  the 
bulb;  op,  the  nerve  of  sight;  oc,  band 
of  fibers  connecting  the  cerebrum  with 
the  cerebellum  and  spinal  cord ;  a,  pons 
Varolii;  h,  medulla  oblongata. 


218         HOW  THE  NERVOUS   SYSTEM  IS  CONSTRUCTED 

of  Sylvius,  above  the   ear,  and   the  fissure  of  Rolando, 

extending  from  the  crown 
obliquely  forward  and  down- 
ward. 

The  General  Structure  of  the 
Brain.  —  A   section  across   the 
brain  shows  it  to  be  composed 
of  a  thin  outer  layer  of  gray 
matter,   called   the    cortex,  and 
near  the   center   other   masses 
of  gray  matter,  while  the  re- 
mainder   appears   white.      EX- 
FIG.  146. -The  brain  from  above,     animation  with  the  microscope 
showing  the  two  hemispheres     shows  that  the  grav  matter  is 

separated  by  the  great  longi- 
tudinal fissure,  composed     ot     very    irregular, 

spherical,  or   oval    cell    bodies 

from    which    extend    threadlike    processes,  called  fibers, 
forming  the  white  matter. 

Each  cell  body  with  all  its 
processes  is  a  true  nerve  cell, 
or  neuron.  There  are  usually 
several  short  processes,  and 
frequently  one  long  process, 
the  axon,'  called  by  the  older 
books  axis  cylinder  process 

._  FIG.   147.  — Cross  section  of  the 

(tig.  148).  Some  of  the 
axones  are  more  than  two  feet 
long  and  extend  from  the  brain 
to  near  the  end  of  the  spinal 
cord.  Axones  are  commonly 
called  nerve  fibers.  Those  which  cross  from  one  side  of 


brain,  c,  band  of  fibers  called 
corpus  callosum.  The  thin 
membrane  around  the  outside 
is  the  dura  mater.  Note  the 
dark  layer  of  gray  matter  or 
cortex  on  the  surface. 


THE   STRUCTURE   OF   THE   SPINAL   CORD 


219 


the  brain  to  the  other  and  connect  parts  of  the  same  name 
form  bands,  known  as  commissures,  like  the  pons  Varolii. 
The  largest  commissure  is  the  corpus  callosum,  uniting  the 
hemispheres  of  the  cerebrum.  Other  fibers  connect  one 
lobe  of  the  cerebrum  with  another. 

The  Spinal  Cord.  —  The  spinal  cord  is  securely  fastened 
in  the  upper  three  fourths  of 
the  canal  of  the  backbone. 
It  is  about  as  thick  as  the 
little  finger,  and  is  surrounded 
by  other  membranes  like  those 
of  the  brain.  It  is  round, 
except  in  the  shoulder  and 
lumbar  region,  where  it  is 
slightly  flattened.  In  these 
two  places  it  is  also  enlarged, 
owing  to  the  great  number  of 
nerve  fibers  joining  it  from 
the  arms  and  legs  (Fig.  142). 

A  deep  crevice,  the  anterior 
fissure,  extending  the  entire 
length  of  the  cord  in  front,  and  a  similar  incision,  the 
posterior  fissure,  incompletely  divide  the  cord  into 
halves. 

The  Structure  of  the  Spinal  Cord.  —  A  cord  cut  into 
crosswise  shows  two  kinds  of  matter  like  that  in  the  brain. 
The  white  substance,  formed  of  fibers,  is  on  the  outside, 
while  the  central  portion  of  the  cord  is  gray  matter,  which 
in  cross  section  appears  H -shaped.  This  gray  matter  is 
made  of  the  body  of  the  nerve  cells.  These  cells  send 
many  of  their  axones,  or  long  processes,  out  to  help  form 


FIG.  148.  —  A  complete  nerve  cell, 
or  neuron,  ax,  long  process 
cat  off;  n,  nucleus. 


220        HOW   THE   NERVOUS   SYSTEM   IS   CONSTRUCTED 

the  nerves  supplying  the  arms,  trunk,  and  legs.  Some  of 
the  fibers  forming  the  white  matter  of  the  cord  convey 
messages  toward,  the  brain,  while  others  carry  messages 
in  the  opposite  direction.  On  any  fiber  the  message 
always  travels  in  the  same  direction. 


FIG.  149.  — Cross  section  of  the  spinal  cord,  showing  nerve  roots  on  one  side. 
ag,  anterior  horn  of  gray  matter;  pg,  posterior  horn  of  gray  matter 
(nerve  cells  are  black;  the  tiny  circles  are  the  ends  of  nerve  fibers  ex- 
tending lengthwise  of  the  cord) ;  ps,  sensory  root ;  an,  motor  root  (these 
two  roots  unite  before  coming  out  between  the  vertebrae) ;  c,  cell  body 

.  whose  fiber  a  extends  to  the  finger;  m,  fiber  extending  to  the  finger 
(arrows  show  the  direction  of  the  impulse ;  only  a  few  of  the  thousands  of 
fibers  actually  present  are  shown) ;  v,  ventral  fissure ;  d,  dorsal  fissure. 


Kinds  of  Nerves.  —  The  cranial  nerves,  of  which  there 
are  twelve  pairs,  are  those  united  to  the  base  of  the  brain. 
The  spinal  nerves,  numbering  thirty-one  pairs,  join  the 
spinal  cord.  Some  of  the  nerves  are  for  the  purpose  of 
transmitting  orders  from  the  central  nervous  system  to 
the  muscles,  and  are  therefore  called  motor  nerves.  The 
sensory  nerves  carry  messages  from  various  parts  of  the 


CRANIAL  NERVES 

body  to  the  spinal  cord  and 
brain.  The  nerve  leading 
from  the  retina  of  the  eye 
is  a  sensory  nerve,  while 
the  nerve  extending  from 
the  brain  to  the  muscles 
to  move  the  eye  is  a 
motor  nerve.  Frequently 
motor  and  sensory  fibers 
are  bound  together  in  the 
same  nerve,  as  is  the  case 
in  all  those  nerves  con- 
nected with  the  spinal 
cord. 

Cranial  Nerves.  —  All  of 
the  twelve  pairs  of  cranial 
nerves,  with  the  exception 
of  one  pair,  supply  the 
head,  neck,  or  upper  part 
of  the  shoulders.  They 
are  numbered  from  before 
backward  according  to  the 
order  in  which  they  are 
joined  to  the  brain.  They 
are  also  named  according 
to  their  function  or  in  ac- 
cordance with  the  region 
which  they  supply.  The 
first  pair  of  cranial  nerves 
are  the  olfactory,  or  nerves 
of  smell,  and  the  second,  or 


FIG.  150.  — View  from  the  side  of  part 
of  the  sympathetic  nervous  system 
within  the  hody  cavity.  The  white 
lines  are  nerves,  a,  spinal  nerves  to 
the  arm;  h,  heart;  i,  intestines;  n, 
ganglia,  or  hunches  of  cell  bodies  on 
the  sympathetic  nerve  cord  ;  p,  one  of 
the  four  large  plexuses  of  the  sym- 
pathetic system ;  t,  stomach ;  10,  tenth 
cranial  nerve  to  lungs  and  stomach. 


222        HOW  THE  NERVOUS   SYSTEM  IS   CONSTRUCTED 

optic,  are  the  nerves  of  sight.  The  eighth  pair  are  the 
auditory  nerves,  leading  from  the  ear. 

Spinal  Nerves.  —  All  the  31  pairs  of  spinal  nerves 
contain  both  motor  and  sensory  fibers.  Each  nerve  is 
united  to  the  cord  by  two  branches,  named  roots,  the  back 
one  of  which  is  the  dorsal  root,  and  the  front  one  is  the 
ventral  root.  If  the  dorsal  root  of  a  spinal  nerve  is  cut, 
the  part  of  the  body  supplied  by  the  nerve  is  without 
feeling,  while  if  the  other  root  is  cut  the  muscles  it  sup- 
plied cannot  be  moved  (Fig.  149). 

The  Nerves  to  the  Limbs.  —  About  200,000  fibers  are 
present  in  the  nerves  in  the  upper  part  of  the  arm.  The 
two  largest  nerves  are  the  median  and  the  musculo-spiral. 
A  continuation  of  one  division  of  the  median  nerve  along 
the  radius  is  the  radial  nerve,  and  the  other  division  along 
the  ulna  is  the  ulnar  nerve. 

Usually  the  larger  nerves,  veins,  and  arteries  lie  to- 
gether, and  are  not  near  the  surface.  The  ulnar  nerve, 
however,  is  so  near  the  surface  at  the  inner  side  of  the 
elbow  that  it  is  often  struck.  It  is  then  usually  said  that 
the  funny  bone  has  been  hit,  because  of  the  queer  feeling 
in  the  ends  of  the  fingers  to  which  the  nerve  extends. 
Several* spinal  nerves  in  the  lumbar  region  are  united  by 
fibers  to  form  a  network  or  plexus,  from  which  branches 
are  distributed  to  the  legs.  The  largest  nerve  of  the  leg 
is  the  sciatic. 

The  Sympathetic  Nervous  System.  —  The  sympathetic 
nerves  connect  all  internal  organs  with  the  central  ner- 
vous system  and  supply  the  glands  and  involuntary  mus- 
cles of  the  entire  body.  This  system  consists  of  three 
parts:  1.  a  nerve  cord  uniting  23  ovoid  ganglia,  lying  on 


SUGGESTIONS   FOR   THE  TEACHER  223 

either  side  and  somewhat  in  front  of  the  spinal  column;  2. 
numerous  fibers  extending  from  these  two  main  cords  and 
ganglia  to  the  viscera,  on  which  they  form  networks,  called 
plexuses;  3.  many  fine  fibers  which  accompany  the  spinal 
and  cranial  nerves  to  supply  the  glands  and  involuntary 
muscles  throughout  the  body  (Fig.  150). 

This  system  is  connected  with  the  main  nervous  system 
by  numerous  branches.  The  will  has  no  direct  control 
over  the  sympathetic  nerves,  which,  against  one's  wish, 
may  refuse  to  make  the  gastric  juice  run  or  may  relax  the 
muscles  of  the  arteries  and  produce  blushing. 

Questions 

1.  Give  the  three  parts  of  the  nervous  system.  2.  What  is  the  re- 
lation of  the  brain  and  spinal  cord  to  the  rest  of  the  body?  3.  Ex- 
plain the  terms  sulci,  fissures,  and  convolutions.  4.  What  connects  the 
brain  with  other  parts  of  the  body?  5.  Give  the  parts  of  the  brain. 
6.  Describe  the  cerebellum.  7.  Give  four  features  of  the  cerebrum. 

8.  What  part  of  a  neuron  composes  the  gray  matter  of  the  brain  ? 

9.  Explain  axon.    10.  What  is  a  commissure?    11.  Give  the  size  and 
location  of  the  spinal  cord.     12.  Of  what  use  are  the  nerve  fibers  ? 
13.  Why  are  some  nerves  called  cranial  and  others  spinal?    14.  How 
does  a  motor  nerve  differ  from  a  sensory?     15.   Nan:e  the  cranial 
nerves  of  sight,  smell,  and  hearing.    16.  To  what  parts  do  most  of  the 
cranial  nerves  extend  ?    17.  Explain  how  a  spinal  nerve  is  attached 
to  the  cord.     18.  State  five  facts  concerning  the  nerves  to  the  limbs. 
19.  Over  what  nerves  does  the  will  have  no  control  ?      20.  To  what 
organs  do  the  nerves  of  the  sympathetic  system  extend? 

Suggestions  for  the  Teacher 

1.  The  brain  of  a  calf  or  sheep  may  be  secured  from  the  butcher. 
Request  him  to  break  it  as  little  as  possible  in  removing  it  from  the 
skull  and  to  leave  the  membranes  on.  Note  the  tough  dura  mater 
which  should  be  cut  loose  with  the  scissors.  The  two  other  membranes 
are  so  thin  that  the  brain  may  be  seen  through  them.  Note  that  the 


224        HOW    THE   NERVOUS   SYSTEM   IS    CONSTRUCTED 

convolutions  are  much  fewer  than  in  the  human  brain,  and  that  the 
cerebrum  does  not  cover  the  cerebellum.  Observe  the  depth  of 
the  fissures  and  the  white  and  gray  matter,  seen  by  cutting  through 
the  brain.  On  the  under  side  look  for  the  two  bands  of  fibers  diverg- 
ing in  front  of  the  pons  Varolii,  the  one  going  to  the  right  and  the 
other  to  the  left  hemisphere.  Through  these,  impulses  travel  to  and 
from  all  parts  of  the  body.  The  brain  may  be  hardened  so  that  it  can 
be  sliced,  by  dropping  it  into  the  formaldehyde  solution  for  a  week. 

2.  A  piece  of  the  spinal  cord  of  a  sheep  or  pig  may  be  had  for 
the  asking  at  the  butcher  shop.     The  arrangement  of  the  white  and 
gray  matter  is  easily  seen,  and  if  care  is  used  in  removing  the  cord,  the 
nerve  roots  may  also  be  seen.     The  nerves  may  be  studied  in  the  hind 
leg  of  a  frog  or  of  a  chicken,  where  they  appear  as  white  glistening 
cords  as  thick  as  a  pin  or  thicker. 

3.  The  interest  of  the  pupils  may  be  greatly  increased  and  lasting 
impressions  may  be  made  by  showing  with  a  microscope  a  thin  slice 
of  the  brain  or  spinal  cord.     If  the  school  has  no  microscope,  a  physi- 
cian may  usually  be  found  in  every  locality  who  will  take  pleasure  in 
showing  the  children  the  wonderful  cells  upon  which  every  thought 
and  movement  depend. 


XX.     HOW  THE  NERVOUS  SYSTEM  WORKS 


The  Use  of  Nerve  Cells.  —  It  is  by  means  of  the  nervous 
system  that  all  parts  of  the  body  are  made  to  work  har- 
moniously. The  muscles  are  directed  when  to  act,  and  the 
stomach  makes  known  its  needs  by  messages  sent  through 
the  nerve  fibers  to  the  cord  and 
brain.  How  the  message  travels 
no  one  knows,  but  it  goes  very 
quickly.  The  time  required  to  send 
a  message  from  a  man's  toe  to  the 
brain  and  back  again  is  about  one 
third  of  a  second.  The  processes 
of  the  nerve  cells  serve  the  same 
purpose  as  the  telegraph  wires  of  a 
railway,  but  the  bodies  of  the  nerve 
cells  are  of  two  kinds.  Those  in  the 
spinal  cord  and  medulla  are  like  the 
telegraph  operator,  and  can  send  only 
such  messages  as  are  given  them. 
The  cell  bodies  in  the  cortex  of  the  brain  are  like  the 
manager  of  the  railway,  and  can  form  the  message  in 
themselves,  and  then  direct  the  nerve  cells  in  the  lower 
parts  of  the  brain  and  in  the  cord  to  send  it  to  a  part 
of  the  body.  How  these  cells  in  the  cortex  of  the  brain 
are  related  to  the  mind  is  not  known. 

DAT.  PHT8.  —  15  225 


FIG.  161.  -  Nerve  cell 
from  the  cortex  of  the 
brain,  a,  axon,  which 
may  extend  to  the  end 
of  the  spinal  cord. 
Magnified. 


226 


HOW   THE   NERVOUS   SYSTEM   WORKS 


How  the  Brain  Acts.  —  Each  part  of  the  brain  has  its 
own  work  to  do.  The  medulla  oblongata  is  the  only  por- 
tion of  the  brain  whose  destruction  causes  immediate 
death.  A  knife  may  be  run  through  the  cerebrum  and 
all  of  the  cerebellum  cut  away  without  fatal  results.  The 

cells  in  the  medulla 
control  the  breathing 
and  the  heart  beat, 
and  also  have  much 
to  do  with  the  motion 
and  secretions  of  the 
alimentary  canal. 

The  use  of  the  cere- 
bellum is  not  well  un- 
derstood. Animals  in 
which  it  is  injured  can 
move  the  muscles,  but 
they  are  unable  to 
contract  at  the  same 
time  and  in  the  right 
degree  the  score  or 


FIG.  152.  —  Skull  cut  away  to  show  parts  of 
the  brain  used  for  various  purposes,  c, 
cerebellum ;  rr,  fissure  of  Rolando ;  I,  cells 
moving  the  leg ;  a,  cells  moving  the  arm ; 
h,  cells  moving  the  hand  ;  /,  cells  moving 


more  of  muscles  nec- 
essary   for     any    act, 


the  muscles  of  the  face ;  t,  cells  receiving 
the  impression  of  touch;  v,  cells  used  in 
seeing ;  e,  cells  used  in  hearing. 

such  as  walking.     As 

a  result  they  tumble  about  like  a  drunken  man.  This 
inability  to  make  the  muscles  act  in  harmony  is  lack  of 
coordination  of  muscular  movements. 

The  Use  of  the  Cerebrum.  —  The  cerebrum  is  the  seat 
of  the  mind.  All  processes  of  thought  depend  upon  the 
nerve  cells  in  this  portion  of  the  brain.  That  part  of  the 
cortex  along  the  front  of  the  fissure  of  Rolando  is  called 


WHAT   THE   SPINAL   CORD   DOES 

the  motor  area,  because  the  cell  bodies  here  are  able  to 
produce  motion  in  all  voluntary  muscles  of  the  body  (Fig. 
152).  A  slight  knock  on  top  of  the  head  causes  one 
to  fall  down,  because  the  cells  of  the  motor  area  are 
stunned.  Most  of  the  long  processes  of  these  cells  extend- 
ing down  through  the  brain  cross  over  to  the  opposite  side 
in  the  medulla  to  form  part  of  the  white  matter  of  the 
spinal  cord.  Therefore  an  injury  to  the  left  hemisphere 
affects  the  muscles  on  the  right  side  of  the  body. 

The  sensory  area  is  along  the  posterior  side  of  the 
fissure  of  Rolando.  The  cells  of  this  region  receive  the 
impulse  aroused  in  the  skin  by  pressure,  heat,  and  cold. 
Destruction  of  all  the  sensory  area  makes  one  insensible  to 
heat,  cold,  and  touch.  The  area  for  sight  is  in  the  cortex 
of  the  back  part  of  the  cerebrum.  If  this  is  destroyed 
one  cannot  distinguish  by  sight  a  ball  from  a  top  or 
a  butterfly  from  a  wasp,  because  the  cells  which  told 
the  mind  the  visible  characters  of  those  things  are 
gone. 

The  area  for  hearing  is  in  the  temporal  lobe,  and  near 
by  are  the  cells  concerned  in  smelling  and  tasting. 

What  the  Spinal  Cord  Does. — The  cord  serves  two  pur- 
poses. It  is  a  path  of  communication  between  the  nerves 
supplying  the  arms,  trunk,  and  legs,  and  the  brain.  An 
impulse  to  kick  starts  from  the  brain's  motor  area,  formed 
by  cell  bodies,  and  passes  along  their  processes  down  the 
spinal  cord  to  the  lumbar  region.  Here  another  set  of  cell 
bodies  receives  the  message,  and  through  their  processes 
forming  part  of  the  sciatic  nerve  carries  it  to  the  muscles 
of  the  leg. 

The  second  function  of  the  cord  is  to  act  independently 


228  HOW   THE   NERVOUS   SYSTEM   WORKS 

of  the  brain  and  produce  many  of  the  muscular  movements 
necessary  in  routine  work.  This  is  spoken  of  as  reflex 
action  (Fig.  153). 

Reflex  Action.  —  This  is  any  action  of  the  nervous  sys- 
tem without  the  use  of  the  will.  Tickling  the  foot  of  the 
soundest  sleeper  causes  it  to  be  moved,  but  the  brain  is 
asleep  and  the  will  did  not  act.  The  cells  in  the  cord 
aroused  by  the  tickling  sent  a  message  to  make  the  mus- 
cles move.  The  squirming  of  a  snake  with  a  mashed 
head,  the  jumping  of  a  chicken  with  its  head  cut  off,  and 
the  wriggling  of  the  pieces  of  a  freshly  cleaned  eel  placed 
in  the  hot  frying  pan  are  reflex  acts  in  which  the  brain 
can  have  no  part. 

Reflex  action  causes  the  hand  stuck  with  a  pin  to  be 
withdrawn  before  the  brain  can  act.  The  stimulus  travels 
up  the  nerve  fibers  of  the  arm  and  through  the  sensory 
cells  of  the  dorsal  root,  then  out  their  processes  to  pass 
over  to  the  motor  cells  in  the  spinal  cord.  These  cells  are 
thus  aroused  to  send  the  message  to  the  muscles  to  con- 
tract. A  twentieth  of  a  second  later  the  brain  is  aware 
of  the  pin,  because  the  sensory  fibers,  upon  entering  the 
cord,  split  and  send  branches  also  up  toward  the  brain 
(Fig.  153). 

The  Use  of  the  Sympathetic  System. — The  working  of  this 
system  consists  of  a  series  of  reflex  actions.  These  nerv'es 
control  the  involuntary  muscle  in  all  parts  of  the  body. 
They  help  govern  the  movements  of  the  intestines  and 
the  heart  beat,  and  determine  the  amount  of  blood  sup- 
plied to  various  parts  of  the  body  by  contracting  or 
loosening  the  muscle  in  the  walls  of  the  small  arteries. 
This  system  regulates  the  activity  of  the  sweat  glands 


urain 


'po 


FIG.  153.  —  Diagram  of  reflex  action.  — Arrows  show  which  way  the  impulse 
is  traveling;  n,  spinal  nerves.  When  the  linger  is  pricked  by  a  tack  t,  the 
nerve  ending  p  receives  the  pain  impulse  and  it  is  carried  along  the  fiber 
a  through  the  sensory  root  around  into  the  spinal  cord.  Here  the  impulse 
is  given  to  the  cell  m,  and  its  fiber  then  conveys  the  impulse  down  the  arm 
to  the  muscle  causing  the  finger  to  be  withdrawn.  The  sensory  fiber 
passing  in  atpo  splits  inside  of  the  cord,  and  one  branch  takes  the  message 
to  the  brain.  Here  it  passes  to  *Jie  motor  cells,  which  may  order  the 
finger  held  still  or  withdrawn. 


230  HOW   THE   NERVOUS    SYSTEM   WORKS 

and  influences  the  secretion  of  the  salivary  glands,  and 
causes  the  flow  of  tears. 

Paralysis  and  Apoplexy.  —  Paralysis  is  inability  of  the 
nerves  to  act  because  of  injury  to  the  cell  bodies  or  the 
processes.  The  breaking  of  a  blood  vessel  in  the  brain  or 
cord,  so  as  to  produce  a  clot  to  press  on  the  cells  or  fibers, 
will  cause  paralysis  in  those  parts  of  the  body  to  which  the 
fibers  help  convey  impulses.  The  growth  of  a  tumor  in 
the  brain  or  the  pressing  of  a  bone  on  nerves  may  also 
result  in  paralysis.  Apoplexy  is  quick  paralysis,  usually 
brought  on  by  the  bursting  or  clogging  of  a  blood  vessel 
in  the  brain. 

How  the  Uses  of  the  Brain  have  been  Determined.  — 
Since  the  dog,  rabbit,  pigeon,  frog,  and  all  other  animals 
with  a  backbone  possess  the  five  parts  of  the  brain  ar- 
ranged in  the  same  order  as  in  man,  much  information 
about  the  use  of  the  brain  has  been  secured  by  experi- 
menting on  the  lower  animals.  In  these  creatures,  put  to 
sleep  by  drugs,  the  effects  of  stimulating  the  nerves  have 
been  noted,  and  the  influence  of  all  parts  of  the  nervous 
system  on  the  various  organs  learned.  Other  knowledge 
has  been  derived  from  studying  those  sick  with  nervous 
ailments,  and  then,  after  death,  cutting  open  the  bodies  to 
see  exactly  where  the  cause  of  the  trouble  was.  Much  of 
the  physiology  of  all  organs  has  been  learned  from  the 
study  of  the  lower  animals.  Experiments  on  them  have 
given*  the  doctors  information  enabling  them  to  save 
thousands  of  human  lives  and  a  vast  amount  of  suffering. 

Brain  Weight  and  Intellect.  —  The  brain  is  smaller  in 
women  than  in  men  because  the  body  is  smaller.  The 
average  weight  of  the  male  brain  is  three  pounds  and  two 


WHY  THE  BRAIN   NEEDS   EXERCISE  231 

ounces,  while  that  of  the  female  is  two  pounds  and  twelve 
ounces.  In  mental  workers  the  brain  grows  until  the 
age  of  40  years,  and  after  the  age  of  50  it  loses  about  one 
ounce  during  every  10  years.  The  brain  of  those  doing 
the  same  work  from  day  to  day,  such  as  shoveling  coal  or 
working  in  a  factory,  so  that  the  mind  is  not  kept  active, 
ceases  to  grow  after  the  twentieth  year  of  age. 

A  good  mind  does  not  depend  so  much  upon  the  size  of 
the  brain  as  upon  the  development  of  the  processes  of  the 
nerve  cells.  In  a  general  way,  however,  the  size  of  the 
cerebrum  and  especially  the  number  of  the  convolutions 
and  the  depth  of  the  sulci  indicate  the  degree  of  intelli- 
gence in  animals.  A  man's  brain  is  larger  than  that  of 
any  other  creature,  except  the  elephant  and  the  whale. 
A  whale  weighing  12,000  pounds  has  a  brain  only  10 
ounces  heavier  than  the  brain  of  a  man  weighing  120 
pounds. 

Why  the  Brain  needs  Exercise.  —  A  muscle  grows  by 
use,  and  the  same  is  true  of  the  brain.  In  the  young 
there  are  many  nerve  cells  with  short  processes  or  none  at 
all.  The  processes  may  be  made  to  develop  by  exercising 
the  cells,  as  when  one  studies.  Thinking  causes  the  blood 
to  flow  to  the  brain,  and  so  brings  more  nourishment  for  the 
cells.  To  express  a  thought  in  one's  own  language  is  worth 
ten  times  more  for  mind  growth  than  to  state  it  in  words 
learned  from  the  book. 

Observing  the  features  of  a  bird  and  then  striving  to 
identify  it  from  the  description  in  the -book,  or  noting  the 
characters  of  a  cow  so  as  to  tell  her  value  compared  with 
other  cows,  develops  important  brain  cells  and  is  worth 
vastly  more  than  memorizing  a  half-dozen  pages  in  a 


232  HOW   THE  NERVOUS   SYSTEM  WORKS 

book.  Professor  Donaldson,  who  examined  the  brain  of 
Laura  Bridgman  deprived  early  of  sight  and  hearing,  says 
that  the  nerve  cells  in  the  sight  and  hearing  areas  of  the 
brain  were  much  smaller  than  those  in  other  persons. 
Like  the  other  tissues,  the  brain,  upon  which  the  mind  de- 
pends, grows  faster  in  youth,  and  no  amount  of  exercise 
will  make  it  develop  late  in  life.  On  this  account  one 
should  hold  steadfastly  to  school  while  young. 

Habits.  —  The  doing  of  one  thing  over  and  over  again 
calls  into  action  the  same  set  of  nerve  cells,  and  they 
finally  become  so  accustomed  to  act  that  they  do  so  with- 
out the  aid  of  the  will  and  often  even  against  it.  This  is 
habit.  A  boy  long  accustomed  to  swearing,  acting  rudely, 
eating  rapidly,  or  looking  sullen  cannot  refrain  from  these 
ungentlemanly  habits  later  in  life,  even  when  honestly  try- 
ing to  do  so.  The  cultivation  of  agreeable  manners  and 
pleasant  looks  not  only  makes  friends  in  school,  but  makes 
success  in  later  life.  Evil  thoughts  passing  often  through 
the  cells  leave  a  blot  there  which  can  never  be  entirely 
erased.  The  first  step  toward  wrong  doing  is  in  wrong 
thinking.  Many  cases  are  known  where  the  reading  of 
books  and  newspapers  describing  wicked  acts  has  affected 
the  nerve  cells  so  as  to  cause  the  reader  to  commit  robbery 
and  other  crimes. 

The  youth  who  causes  to  pass  through  his  nervous 
system  into  the  mind  noble  thoughts  from  good  people 
and  good  books,  and  who  learns  industry,  patience,  and 
politeness,  is  sure  of  friends  and  success  in  life.  The 
mind  is  like  a  piece  of  ground  which,  if  not  sowed  with 
good  seed  and  cultivated,  will  grow  up  with  worthless 
weeds.  It  is  therefore  important  that  one  should  keep 


THE   NERVOUS    SYSTEM    AND    TOBACCO  233 

the  mind  busy  in  doing  what  will  yield  the  right  kind  of 
harvest. 

Sleep. — It  is  just  as  important  to  rest  as  to  work. 
The  only  time  when  the  nervous  system  rests  completely 
is  during  sleep.  Adults,  as  a  rule,  should  sleep  eight 
hours  every  night,  while  those  younger  should  add  fifteen 
minutes  for  every  year  under  the  age  of  twenty.  Loss  of 
sleep  is  sure  to  result  in  ill  health  sooner  or  later.  The 
time  for  retiring  should  be  the  same  every  night,  so 
that  one  will  drop  off  to  sleep  within  five  minutes  after 
lying  down.  Without  the  advice  of  a  physician  medicine 
should  never  be  taken  to  produce  sleep.  Placing  the  feet 
in  hot  water  a  few  minutes,  taking  a  hot  bath,  or  a  half 
glass  of  hot  milk  is  an  aid  to  sleep. 

The  Nervous  System  and  Tobacco.  —  Tobacco  habitually 
used  by  the  young  has  a  more  serious  effect  on  the  ner- 
vous system  than  on  any  other  part  of  the  body.  It  pre- 
vents the  brain  cells  from  developing  to  their  full  extent 
and  results  in  a  slow  and  dull  mind.  Justice  Brewer, 
of  the  United  States  Supreme  Court,  says :  "  No  ciga- 
rette smoker  can  attain  the  highest  position  in  the  world." 
At  Harvard  University  during  fifty  years  no  habitual 
user  of  tobacco  ever  graduated  at  the  head  of  his  class. 
The  New  York  Division  of  the  Reading  Railroad,  which 
prohibits  cigarette  smoking  by  employees,  says  :  ^  Men  who 
smoke  cigarettes  are  liable  to  lapses  of  memory,  and  it  is 
not  safe  to  trust  the  lives  of  passengers  in  the  hands  of 
men  who  have  that  failing." 

Recent  careful  investigations  by  many  persons  show 
that  cigarette  smoking  not  only  clouds  the  intellect,  but 
tends  to  make  criminals  of  boys.  Dr.  Hutchison,  of 


234  HOW   THE  NERVOUS   SYSTEM   WORKS 

the  Kansas  State  Reformatory,  says:  "Using  cigarettes 
is  the  cause  of  the  downfall  of  more  of  the  inmates  of  this 
institution  than  all  other  vicious  habits  combined."  Of 
4117  boys  received  into  the  Illinois  State  Reformatory, 
4000  were  in  the  habit  of  using  tobacco,  and  over  3000 
were  cigarette  smokers. 

It  is  unwise  to  begin  the  use  of  tobacco,  because  when 
the  habit  is  once  acquired  it  can  be  broken  only  by  one 
with  a  strong  mind  who  is  willing  to  endure  suffering 
caused  by  the  longing  nerve  cells  during  the  first  few 
weeks  after  being  deprived  of  their  accustomed  poison. 

How  Alcohol  affects  the  Nervous  System.  — Much  of  the 
alcohol  consumed  is  absorbed  by  the  blood  vessels  of  the 
stomach,  so  that  it  reaches  the  nerve  cells  in  a  few  minutes. 
A  large  amount  of  alcohol  paralyzes  them,  as  may  be 
judged  by  the  actions  of  a  reeling  drunken  man.  In 
many  persons  a  half  teacupful  of  strong  wine  will  affect 
the  brain  perceptibly. 

A  drink  of  whisky  or  wine  may  help  one  to  talk  more, 
because  it  removes  the  careful  judgment  which  one 
should  give  a  thought  before  he  utters  it.  On  this  ac- 
count persons,  after  drinking,  often  reveal  secrets  and 
say  very  silly  things.  All  late  investigators  declare  that  a 
student  can  perform  more  mental  work  in  a  day  without 
alcohol  than  he  can  by  the  aid  of  either  small  or  large 
quantities  of  any  alcoholic  drink.  The  excessive  use  of 
alcoholic  drinks,  whether  pure  or  impure,  may  cause  delir- 
ium tremens.  This  is  a  severe  poisoning  of  the  nerve  cells, 
resulting  in  trembling,  weakness,  and  great  fear.  Often 
the  victim  thinks  he  sees  horned  animals,  spitting  insects, 
and  snakes. 


HOW    ALCOHOL   AFFECTS   THE   NERVOUS   SYSTEM      235 

The  continued  use  of  liquor  in  many  cases  produces  a 
gradual  change  in  the  nerve  cells  so  as  to  affect  the  mind 
and  cause  a  tendency  to  crime.  This  fact  is  very  clearly 
shown  by  the  careful  investigations  of  the  Committee  of 
Fifty,  who  inquired  into  the  history  of  13,402  convicts, 
and  ascertained  that  intemperance  was  a  strong  factor  in 
the  downfall  of  over  6000  of  them.  Alcohol  was  the 
first  cause  of  crime  in  over  4000  of  these  convicts.  The 
government  report  of  Massachusetts  states  that  one  sixth 
of  all  of  the  crime  in  that  state  is  due  solely  to  alcohol. 
Russia  reports  that  one  fourth  of  her  crime  results  from 
alcohol.  Intemperance  causes  a  little  over  one  half  of  the 
crime  in  England. 

The  mind  cannot  be  strong  and  sound  when  the  brain 
cells  are  being  constantly  injured  by  large  daily  doses  of 
beer,  wine,  or  whisky.  Numbing  the  cells  of  the  brain  or 
affecting  them  in  any  way  by  alcoholic  drink  always  has 
some  influence  on  the  mind.  The  reports  of  the  Com- 
missioners of  various  insane  asylums  show  that  nearly 
one  fourth  of  the  male  persons  confined  in  them  owe 
their  insanity  to  alcohol.  The  report  of  the  Waterford 
Lunatic  Asylum  in  Ireland  for  1903  states  that  the  most 
frequent  cause  of  insanity  of  those  admitted  was  in- 
temperance. 

The  poisonous  effects  of  alcohol  on  the  nervous  system 
of  the  parent  are  in  many  cases  transmitted  to  the  chil- 
dren. Havelock  Ellis  says  that  some  of  the  most  charac- 
teristic cases  of  criminality  in  children  are  solely  or 
chiefly  due  to  the  use  of  strong  drink  by  the  parents. 
Dr.  Keer  reports  that  in  one  family  after  the  birth  of 
a  healthy  son  and  later  a  healthy  daughter,  the  father 


236  HOW   THE   NERVOUS   SYSTEM   WORKS 

became  a  drunkard.     Of  the  four  children  born  after  this, 
three  were  idiots. 

Professor  Hodge,  of  Clark  University,  tells  of  10  alco- 
holic families  in  which  there  were  57  children,  and  only 
ten  of  them  were  healthy.  Some  were  idiots  and  some 
were  epileptics.  There  are  about  200,000  idiots  and  epi- 
leptics in  the  United  States,  and  it  is  probable  that  some 
of  them  owe  their  condition  to  the  drunkenness  of  their 
parents.  During  the  next  ten  years  after  the  spirit  tax 
was  removed  in  Norway,  drunkenness  increased  markedly 
and  the  proportion  of  idiots  born  increased  150  per  cent. 
Scientific  investigations  confirm  the  warning  of  the  Scrip- 
ture :  "  The  sins  of  the  parents  shall  be  visited  upon  the 
children  even  unto  the  third  and  fourth  generation." 

Questions 

1.  How  do  the  nerve  fibers  differ  in  function  from  the  cell  bodies? 
2.  Explain  the  use  of  the  medulla.  3.  What  work  does  the  cerebellum 
perform  ?  4.  Upon  what  part  of  the  brain  does  thought  largely  de- 
pend? 5.  What  is  meant  by  motor  area?  6.  Explain  the  sensory 
area.  7.  What  are  the  two  uses  of  the  spinal  cord  ?  8.  Explain  reflex 
action.  9.  What  causes  paralysis?  10.  How  have  the  uses  of  the 
different  parts  of  the  brain  been  learned  ?  11.  Give  some  facts  con- 
cerning the  weight  of  the  brain.  12.  What  elements  in  the  brain 
determine  the  making  of  a  good  mind?  13.  How  can  one  increase 
the  amount  of  nourishment  carried  to  the  brain?  14.  Why  should 
you  not  memorize  the  words  of  your  lesson  ?  15.  Why  is  it  important 
to  exercise  the  brain  in  youth  ?  16.  What  habits  are  dangerous  and 
why?  17.  State  five  facts  about  sleep.  18.  What  effect  has  alcohol 
on  the  nervous  system  ?  19.  Explain  the  cause  of  delirium  tremens. 

Suggestions  for  the  Teacher 

Ask  some  of  the  pupils  to  tell  how  they  have  been  able  to  stop  some 
bad  habits,  such  as  chewing  the  finger  nails,  speaking  in  a  loud  and 
rude  manner,  or  frowning. 


XXI.     THE   SENSE  ORGANS 

The  Nature  of  the  Sense  Organs.  —  The  sense  organs  are 
the  terminations  of  the  sensory  nerves  serving  to  carry 
impressions  to  the  spinal  cord  or  brain.  They  are  the 
means  by  which  all  messages  of  information  get  on  to 
the  nerves  to  be  carried  to  the  central  nervous  system. 
One's  knowledge  of  an  apple  is  secured  through  certain 
sense  organs  in  the  skin  touching  the  apple,  through  the 
sense  organs  in  the  nose  affected  by  the  odor  of  the  apple, 
through  the  sense  organs  in  the  tongue  aroused  by  its 
sweetness,  and  through  the  sense  organs  of  sight  stimulated 
by  the  light  reflected  from  the  apple. v  None  of  these  im- 
pulses excited  in  the  sense  organs  can  give  rise  to  sensa- 
tions until  they  reach  the  brain.  A  man  had  his  back 
broken  so  that  the  bones  pressed  on  the  cord,  preventing 
its  nerves  from  carrying  any  message  up  to  the  brain. 
When  his  feet  were  tickled,  the  legs  would  jump  about, 
showing  that  the  sense  organs  of  the  skin  had  sent  the 
stimulus  up  the  nerves  to  the  cord,  exciting  an  impulse  in 
the  motor  cells  there,  but  the  man  said  he  felt  no  touch  on 
the  feet.  No  sensation  of  tickling  was  produced,  because 
the  impulse  received  by  the  organs  of  sense  could  not 
reach  the  brain. 

The  Kinds  of  Senses.  —  Two  general  classes  of  senses 
are  known.  The  interior  or  general  senses  are  those  tell- 
ing a  person  of  the  condition  of  the  body.  To  this  class 

237 


238 


THE    SENSE    ORGANS 


belong  the  senses  of  hunger,  pain,  thirst,  and  fatigue. 
The  exterior  senses  are  the  special  senses,  such  as  those 
of  temperature,  pressure,  smell,  taste,  hearing,  and  sight. 
The  senses  of  temperature,  pressure,  and  pain,  which  the 
older  books  call  the  sense  of  touch,  are  now  known  to  be 
just  as  different  from  each  other  as  sight  and  hearing. 

The  Senses  of  the 
Skin.  —  These  are 
often  called  cutaneous 
senses  and  include 
temperature,  pressure, 
and  pain.  There  are 
certain  nerves  with 
their  special  endings 
scattered  throughout 
the  skin  to  receive 
the  stimulus  of  cold, 
and  an  entirely  dif- 
ferent set  of  nerves 

FIG.  154.  — Section  of  the  skin  showing  various      and    Sense    Organs    to 


receive     the    knowl- 


kinds  of  nerve  endings  at  om,  m,  e,  and  a ; 
h,  hair. 

edge   of  heat.       The 

sharp  point  of  an  icicle  can  be  placed  on  certain  very 
small  spots  of  the  skin  without  any  cold  being  felt, 
because  the  sense  organs  for  cold  are  in  many  places  a 
quarter  of  an  inch  or  more  apart. 

The  sense  organs  for  pressure  are  the  nerve  endings 
around  the  roots  of  hairs,  and  where  these  are  absent 
minute  oval  bulbs,  called  tactile  corpuscles,  occur.  A  hair 
cannot  be  disturbed  ever  so  gently  without  a  sensation 
of  touch  or  delicate  pressure.  The  lining  of  the  alimen- 


THE  SENSE   OF   SMELL 


239 


tary  canal  below  the  mouth  does  not  possess  any  sense 
organs  of  temperature  or  pressure,  and  therefore  the 
movement  of  the  food  is  not  felt  except  when  sickness 
makes  the  end  organs  of  pain  more  sensitive. 

The  sense  of  pain  has  separate  nerves  with  their  organs 
of  sense  widely  dis- 
tributed throughout 
the  body.  This  sense 
is  of  great  service  in 
telling  an  individual 
when  any  of  the 
organs  are  sick  or 
are  being  injured. 
Freezing  or  an  ap- 
plication of  cocaine 
numbs  the  sense 
organs  of  pain  and  is 
often  used  in  opera- 
tions by  the  surgeon. 

The  Sense  of  Smell. 

FIG.  155.  —  Section  through  the  nose,    a,  dis- 

—  Ihe    Sense    organs         tribution  of  the  nerve  of  smell  connected 

with  ol,  the  olfactory  lobe  lying  beneath  the 
fore  part  of  the  brain. 


of  smell   are  located 
the  mucous  mem- 


m 

brane  lining  the  upper  part  of  the  cavity  of  the  nose. 
They  consist  of  hundreds  of  long  columnar  cells,  each  of 
which  bears  on  its  outer  end  from  six  to  eight  hairlike 
processes.  Particles  of  matter  in  the  form  of  gas, 
striking  these  processes,  send  a  stimulus  by  the  olfactory 
nerves  to  the  brain,  producing  the  sensation  of  smell. 

A  cold  excites  a  secretion  of  mucus  in  the  nose  so  as 
partly  to  cover  the  organs  of  smell,  and  also  results  in  an 


240 


THE  SENSE   ORGANS 


inflammation  of  the  membrane  bearing  them,  so  that  they 
are  not  able  to  act.  During  a  cold  many  foods  seem  to 
have  little  taste,  because  it  is  the  odor  rather  than  the 
taste  that  gives  the  desired  quality  to  some  eatables. 
The  pleasure  from  eating  onions,  coffee,  and  cheese  will 

be  greatly  lessened 
if  one  holds  his 
nostrils  shut. 

The  Sense  of 
Taste.  —  The  end 
organs  for  taste 
occur  in  the  mucous 
membrane  of  the 
tongue,  soft  palate, 
and  other  regions  of 
the  throat.  They 
are  minute  oval 
bodies,  called  taste 
buds,  each  of  which 
is  connected  with  a 
nerve  fiber  extend- 
ing to  the  brain. 

The  taste  buds  are  most  abundant  in  the  dozen  or  less 
circumvallate  papillce,  at  the  back  of  the  tongue,  and  in 
the  fungiform  papilloe,  appearing  as  white  dots  all  over 
the  top  of  the  tongue  (Fig.  91). 

A  substance  can  arouse  the  sense  of  taste  only  when  in 
the  form  of  a  liquid  or  dissolved  in  a  liquid.  It  is  im- 
portant that  all  food  should  be  chewed  many  times  and 
dissolved  as  completely  as  possible  in  the  mouth  so  as  to 
affect  the  taste  buds.  This  causes  the  gastric  juice  to 


FIG.  156.  —  Section  through  one  side  of  a  large 
papilla  on  the  tongue,  showing  five  taste  buds 
and  the  nerve  of  taste,  n. 


THE   SENSE   OF   HEARING 


241 


flow  abundantly.  Careful  experiments  teach  that  chew- 
ing each  mouthful  thirty  times  will  do  more  to  cure 
dyspepsia  than  all  medicines  combined. 

The  Sense  of  Hearing.  —  The  organs  of  hearing  are  the 
ears.     Each  one  consists  of  three  parts,  named  the  external 


FIG.  157.  —  Temporal  bone  cut  open  to  show  the  bony  internal  ear.  c,  coch- 
lea ;  v,  vestibule ;  sem,  semicircular  canals ;  m,  middle  ear ;  d,  malleus ; 
t,  tympanic  membrane ;  n,  auditory  nerve.  The  internal  and  middle  ear 
are  shown  about  double  natural  size. 


ear,  the  middle  ear,  and  the  internal  ear.  The  external 
ear  is  composed  of  the  pinna,  projecting  from  the  side  of 
the  head,  and  the  tube,  an  inch  long,  called  the  auditory 
canal,  extending  inward.  Across  the  inner  end  of  the 
canal  is  a  thin  membrane,  named  the  tympanic  membrane. 
The  cavity  of  the  middle  ear,  or  tympanum,  also  called 
ear  drum,  is  nearly  large  enough  to  contain  three  pennies 
standing  close  together  on  their  edges.  It  contains  air 

DAV.   PHYS.  —  16 


242  THE   SENSE    ORGANS 

which  may  pass  in  and  out  through  the  Eustachian  tube 
leading  to  the  throat.  The  mouth  of  the  tube  is  usually 
closed,  but  it  opens  every  time  a  bit  of  food  or  even  saliva 
is  swallowed.  Three  bones,  the  malleus,  or  hammer,  incus, 
or  anvil,  and  stapes,  or  stirrup,  form  a  chain  stretching 
from  the  tympanic  membrane  to  another  membrane 
closing  an  oval  opening  into  the  internal  ear  (Fig. 
157). 

The  internal  ear,  or  labyrinth,  is  composed  of  several 
irregular  connected  cavities  in  the  temporal  bone  contain- 
ing within  them  correspondingly  shaped  membranous  sacs 
supporting  the  end  organs  of  the  nerve  of  hearing.  The 
three  parts  of  the  internal  ear  are  the  vestibule,  cochlea,  and 
the  three  semicircular  canals.  The  bony  cavities  are  filled 
with  a  watery  fluid,  called  perilymph,  serving  to  float  the 
delicate  membranous  parts  containing  a  similar  fluid,  the 
endolymph. 

The  fluid  in  the  bony  vestibule  about  the  size  of  a  pea 
is  separated  from  the  cavity  of  the  tympanum  at  one  place 
by  a  mere  membrane  to  which  is  fixed  the  foot  of  the  stapes. 
The  semicircular  canals  are  bent  tubes  placed  at  right 
angles  to  each  other.  They  have  nothing  to  do  with  hear- 
ing, but  enable  one  to  balance  the  hody  and  know  its  posi- 
tion even  with  the  eyes  closed. 

The  cochlea,  so  named  from  its  resemblance  to  a  snail 
shell,  is  a  coiled  tube  having  three  coils,  with  those  nearer 
the  center  becoming  successively  smaller  and  more  ele- 
vated. On  the  interior  of  the  membranous  cochlea  is 
located  the  sense  organ  of  hearing,  consisting  of  columnar 
cells  with  hairlike  processes  projecting  into  the  endo- 
lymph. 


DEAFNESS  243 

How  Sound  is  Heard.  —  The  striking  of  a  hard  object, 
the  crack  of  a  gun,  or  any  other  similar  action  disturbs 
the  air  and  causes  in  it  waves  like  the  waves  produced  in 
water  by  a  stone  cast  into  a  quiet  pool.  The  sound  waves 
are  vibrations  of  particles  of  air  which  knock  against  the 
delicate  tympanic  membrane.  This  causes  motion  in  the 
chain  of  bones  of  the  middle  ear,  and  these  in  turn  trans- 
mit the  vibration  to  the  perilymph  of  the  inner  ear,  touch- 
ing the  membrane  attached  to  the  foot  of  the  stapes. 
The  waves  in  the  perilymph  beat  on  the  delicate  mem- 
branous part  of  the  cochlea,  and  thus  make  vibrations  in 
the  endolymph  which  affect  the  hairlike  processes  on  the 
cells  at  the  termination  of  the  nerve  fibers  of  hearing. 
These  fibers,  forming  the  auditory  or  eighth  cranial  nerve* 
conduct  the  stimulus  to  the  brain. 

The  Care  of  the  Ears.  —  Hard  objects,  such  as  pencils 
and  sticks,  should  not  be  pushed  into  the  external  ear  for 
fear  of  breaking  the  ear  drum.  The  wax,  which  tends  to 
keep  insects  and  dirt  from  lodging  on  the  tympanic  mem- 
brane, sometimes  collects  in  too  large  quantities  in  the 
canal.  It  may  then  be  removed  with  the  round  end  of  a 
wire  hairpin.  Insects  finding  their  way  into  the  ear  may 
be  killed  or  made  .to  come  out  by  putting  in  a  few  drops 
of  warm  soapy  wa1 ;  or  while  the  patient  is  in  a  reclining 
position,  with  the  aiVected  ear  uppermost.  In  ten  minutes 
the  ear  may  be  turner!  down  on  the  pillow,  when  the  water 
will  flow  out  and  carij  the  insect  with  it. 

Deafness.  —  The  ear  is  a  very  delicate  organ,  and  injury 
to  any  of  its  parts  may  result  in  deafness.  A  box  on  the 
ears  may  rupture  the  ear  drum,  but  in  many  cases  nature 
will  mend  this  break.  Closure  of  the  Eustachian  tube  by 


244  THE   SENSE   ORGANS 

catarrh,  so  that  the  pressure  of  the  air  in  the  middle  ear 
cannot  be  made  equal  with  that  outside,  sometimes  causes 
partial  deafness.  A  growth  of  germs  in  the  tympanum, 
producing  an  inflammation,  as  in  running  ears,  may  make 
the  three  little  bones  grow  together  solidly  at  their  ends, 
and  then  they  cannot  move  freely  to  transmit  sound.  More 
than  half  of  the  school  children  in  the  United  States 
suffer  from  a  defect  in  the  ears,  eyes,  nose,  or  throat. 

The  deaf  and  dumb  are  unable  to  hear  because  the 
sense  organ  in  the  cochlea  is  imperfect.  Some  cases  of 
deafness  resulting  from  disease  or  accident  can  be  cured, 
but  one  should  never  pay  attention  to  the  numerous  ad- 
vertisements in  newspapers  and  magazines  offering  to 
cure  deafness.  They  are  the  words  of  quack  doctors  who 
rob  people  of  thousands  of  dollars  and  are  likely  to  dam- 
age the  ear  seriously.  An  honest  physician  does  not  ad- 
vertise a  sure  cure  for  deafness,  but  does  all  in  his  power  to 
enable  his  patients  to  recover  their  hearing. 

Questions 

1.  Explain  the  nature  of  sense  organs.  2.  Name  eight  senses. 
3.  Name  the  senses  having  organs  located  in  the  skin.  4.  Of  what 
use  are  the  sense  organs  ?  5.  Why  do  we  not  feel  the  particles  of  food 
brushing  against  the  sides  of  the  stomach?  6.  Describe  the  sense 
organ  of  smell.  7.  Explain  the  sense  of  taste.  8.  Give  the  three 
parts  of  the  organ  of  hearing.  9.  Describe  the  middle  ear. 
10.  Name  the  three  parts  of  the  internal  ear.  11.  How  is  the  fluid 
arranged  in  the  internal  ear  ?  12.  Of  what  use  are  the  semicircular 
canals?  13.  Explain  the  location  and  use  of  the  cochlea.  14.  De- 
scribe how  sound  is  heard.  15.  Give  some  points  in  reference  to  the 
care  of  the  ears.  16.  What  may  cause  deafness  ?  17.  Why  is  it  un- 
wise to  patronize  doctors  who  advertise  to  cure  deafness  ?  18.  Test 
each  ear  by  closing  oi\e  with  the  finger  and  then  listening  to  the  tick 
of  a  watch  in  a  distant  part  of  the  room. 


SUGGESTIONS   FOR   THE   TEACHER  245 


Suggestions  for  the  Teacher 

1.  Let  the  children  test  the  sense  of  taste  on  different  portions  of 
the  tongue  by  placing  bits  of  sugar  and  salt  on  various  regions  of  the 
tongue. 

2.  Test  the  hearing  of  the  pupils  by  placing  a  ticking  watch  at 
varying  distances  from  them.     Ask  the  pupils  to  note  through  "which 
ear  they  hear  the  more  distinctly.     The  test  can  be  made  by  closing 
one  of  the  ears  with  the  finger.     It  is  important  that  the  teacher  may 
discover  any  defects  in  the  hearing  among  the  children,  as  dullness  and 
apparent  stupidity  are  often  due  to  some  diseased  condition  of  the  ears 
which  may  in  early  life  be  corrected  by  a  physician.     The  children 
who  do  not  hear  distinctly  should  always  be  given  the  front  seats. 

3.  The  teacher  may  render  a  great  service  to  any  pupil  partially 
deaf  by  talking  the  matter  over  with  the  parents  and  impressing  upon 
them  the  danger  of  patronizing  quack  doctors,  and  the  need  of  an 
immediate  examination  and  advice  by  a  physician.     It  is  well  to 
remember  that  in  many  cases   partial  deafness   has  resulted  from 
adenoid  growths  described  on  page  147. 


XXII.    THE   SENSE   ORGANS   (Continued) 


THE  EYE 

The  Location  of  the  Eye.  —  The  dome-shaped  cavities  in 
the  front  of  the  skull  and  just  below  the  region  of  the 
eyebrows  are  the  orbital  cavities,  in  which  the  eyeballs  are 
lodged.  Thick  layers  of  fat  within  each  cavity  make 

a  secure  resting 
place  for  the  eye- 
ball, which  is  held 
loosely  by  six  mus- 
cles and  the  optic 
nerve.  The  optic, 
•or  second  pair  of 
cranial  nerves, 
pass  through  holes 
in  the  skull  to  the 
brain  and  serve 

FIG.  168.  —  Side  of  the  orbital  cavity  cut  out  to  to  convey  the  im- 
show  the  muscles  moving  the  eyeball,  o,  optic  pressions  ma(ie  by 
nerve  ;  a,  muscle  cut  loose.  *• 

light. 

How  the  Eyeball  is  Moved.  —  Four  muscles  attached  to 
the  upper,  lower,  outer,  and  inner  surfaces  of  the  ball  are 
connected  with  the  bones  in  the  back  part  of  the  orbit. 
These  are  called  recti  muscles,  because  they  are  straight. 
A  contraction  of  the  inner  one  turns  the  ball  toward  the 
nose,  while  the  outer  one  pulls  in  the  opposite  direction, 

246 


THE   WALLS   OB   COATS   OP   THE   EYEBALL 


247 


and  the  upper  and  lower  muscles  turn  the  ball  upward 
and  downward  respectively.  Two  oblique  muscles  give 
other  motions  to  the  ball.  Cross  eyes  are  caused  by  the 
inner  recti  muscles  being  stronger  than  the  outer  ones. 

The  Parts  of  the  Eye.  —  The  complete  eye  consists  of 
the  eyebrows,  which 
prevent  the  perspira- 
tion from  running 
down  into  the  eyeball, 
the  eyelids,  which 
protect  the  eyeball 
in  front,  and  the  eye- 
ball itself.  The  eyeball 
is  nearly  spherical, 
and  consists  of  an 
outer  wall  one  tenth 
of  an  inch  thick  filled 
with  three  transparent 
substances,  called  hu- 
mors. As  the  eye  of  FIG.  159.  —  Horizontal  section  through  the 

oow   nio-    or  pa.fr   has        eye<     a'  a(lueous  humor;    «c»  fovea5    b* 

blind  spot;  ci,  fibers  of  ciliary  muscle;  co, 

the   Same   Structure    as         cornea;  ch,  choroid  coat;  ir,  iris;  /,  crys- 
i  ,1         I-  talline lens ;  n,  ciliary  processes;  op,  optic 

a  human  eye,  the  dis-       nerve.  s>  ^^  c^tp 

section  or  cutting  apart 

of  the   eyeball   of  any   one   of   these  animals  will   be  a 

great  help  to  pupils  in  their  study  of  the  orgaii  of  sight. 

The  Walls  or  Coats  of  the  Eyeball. — The  wall  of  the 
eyeball  is  composed  of  three  coats.  The  outer  coat  consists 
of  the  tough  and  thick  sclerotic  part  behind,  and  the  trans- 
parent cornea  in  front.  The  middle  coat,  about  as  thick  as 
paper,  is  formed  largely  of  the  black  choroid  portion,  con- 


248  THE   SENSE   ORGANS 

tinuous  in  front  with  the  iris  appearing  blue,  gray,  or 
brown  according  to  the  color  of  the  eye.  A  circular 
opening  in  the  center  of  the  iris  is  the  pupil,  through 
which  light  passes  to  the  interior  (Fig.  159).  By  means 
of  muscular  fibers  forming  part  of  the  iris  the  pupil  is 
made  to  vary  in  size  so  as  to  regulate  the  amount  of  light 
reaching  the  inner  coat  of  the  eye.  A  bright  light  dimin- 

nishes  the  size  of 
the  pupil.  The 

inner  coat  of  the 

eyeball  is  the  ret- 
ina. It  is  thinner 
than  the  paper  of 

FIG.  160.  —  Diagram  showing    how  the  convex  .   .         , 

lens  na  brings  the  rays  of  sunlight  to  a  focus  this       book,      very 

at/.    Note  how  the  ray  is  bent  at  b  and  also  at  tender,    and    of     a 
d,  while  the  ray  at  n  or  a  is  not  affected. 

pinkish  white  color. 

It  is  made  of  connective  tissue  and  nerve  matter,  and 
forms  the  end  organ  of  the  optic  nerve. 

The  Humors  of  the  Eye.  —  The  interior  of  the  eyeball  is 
divided  into  two  chambers  by  the  most  solid  humor,  called 
the  crystalline  lens.  The  anterior  chamber,  between  the 
cornea  and  lens,  is  filled  with  a  watery  fluid,  known  as 
the  aqueous  humor.  The  much  larger  posterior  chamber  is 
occupied  by  the  vitreous  humor,  which  appears  like  a 
colorless  jelly. 

If  the  posterior  half  of  the  wall  of  a  cow's  eyeball, 
freshly  secured,  is  cut  away  with  the  scissors  and  the  ball 
then  laid  so  that  the  cornea  rests  on  fine  print,  the  letters 
will  appear  greatly  magnified.  The  crystalline  lens, 
which  is  held  in  place  by  a  delicate  ligament  attached 
where  the  cornea  unites  with  the  sclerotic  coat,  may  be 


THE   NATURE   OF   LIGHT 


249 


removed  and  supported  on  a  paper  with  a  small  hole  and 
used  temporarily  for  a  magnifying  glass. 

The  Nature  of  Light.  —  Light  is  pro'duced  by  the  waves 
or  vibrations  of  a  substance  called  ether.  It  is  present 
in  all  space,  and  even  where  air  does  not  exist.  The 
waves  of  ether  aroused  by  the  sun  or  lamp  make  impres- 
sions on  the  retina, 
which  are  trans- 
mitted to  the  brain 
by  the  fibers  of 
the  optic  nerve. 
Many  ob  j  ec  ts,  such 
as  a  pencil  or  a 
table,  have  no 
power  in  them- 
selves to  produce 
light,  but  they 
reflect  or  throw 


Fio.  161.  —  Diagram  of  the  shape  of  the  lens;  A, 
when  viewing  far  objects;  B,  when  viewing 
near  objects ;  a,  ligament  of  the  lens ;  e,  attach- 
ment of  ciliary  muscle  m  which  in  B  is  con- 
tracted so  as  to  draw  forward  the  choroid  coat 
at  n  and  thus  loosen  the  ligament  of  the  lens. 


back  the  light 
waves  started  by 
the  candle  or  sun. 

The  waves  of  light  are  like  the  waves  in  water  caused 
by  tossing  a  stone  into  it,  but  they  travel  much  faster. 
The  rate  of  progress  is  about  186,000  miles  per  second. 
They  travel  in  straight  lines.  Each  of  the  millions  of 
lines  of  light  radiating  from  an  object  in  all  directions  is 
called  a  ray.  Substances  like  glass,  which  permit  the 
rays  of  light  to  pass  through  them  readily,  are  said  to  be 
transparent.  A  ray  of  light  passing  through  a  glass  with 
curved  surfaces  may  have  its  direction  changed,  as  seen  in 
the  diagram. 


250 


THE   SENSE   OKGANS 


The  Bending  of  the  Rays  of  Light.  —  A  ray  of  light 
passing  through  glass  whose  surface  it  does  not  strike 
perpendicularly  is  bent  out  of  its  direct  course.  A  piece 
of  glass  whose  opposite  surfaces  curve  outward  forms  a 
convex  lens,  while  one  with  the  opposite  surfaces  curving 

inward  toward  each 
other  is  a  concave  lens. 
Rays  of  light  passing 
through  a  convex  lens 
are  made  to  converge 
so  that  all  meet  in  one 
point  called  the  focus, 
as  shown  in  the  figure. 
The  Process  of  Seeing. 
—  In  order  that  the  ret- 
ina may  be  stimulated 
in  a  way  to  give  the 
FIG.  162.  —  Diagram  showing  how  near-  brain  a  clear  image  of 

•  sightedness  as  in  B  and  farsightedness  as      any   obl'ect,  the    rays   of 
in  A  can  he  corrected  by  glasses.     The  ^ 

dotted  lines  show  how  the  rays  of  light      light   Coming    from    the 


are  affected  hy  the  glasses,  while  the  un- 
broken  lines  show  the  direction  of  the 
rays  when  the  glasses  are  not  present. 


object  mugfc  be  madet  to 
meet  at  one  point  Oil  the 

retina.     To  effect  this, 

the  crystalline  lens  is  convex.  Since  the  rays  passing 
through  the  lens  near  its  edge  are  bent  more  than  those 
passing  through  near  the  center,  it  is  necessary  to  have 
behind  the  crystalline  lens  another  lens,  the  vitreous 
humor.  This  together  with  the  aqueous  humor  so  acts 
as  to  bring  the  rays  to  one  point  on  the  retina. 

The  eyeballs  are  so  held  by  the  muscles  that  the  rays 
of  light  coming  from  an  object  are  focused  on  a  corre- 


Y  F  E  V 


NEAKSIGHTEDNESS  251 

spending  area  in  each  eye.  This  area,  called  thefovea,  or 
point  of  acute  vision,  is  a  quarter  of  an  inch  to  the  outer 
side  of  where  the  optic  nerve  pierces  the  eyeball.  After 
slightly  rotating  one  eyeball  by  pushing  on  it  with  the 
finger,  the  rays  of  light  will  not  strike  the  fovea  in  that 
eye,  and  consequently  the  object  will  appear  double. 

The  Power  of  Accommodation.  —  The  change  frequently 
taking  place  in  some  parts  of  the  eye  in  order  that  it  may 
see  distinctly  objects  that  are  near  by  or  those  far  off,  is 
called  accommodation.  After  reading  several  hours,  the 
eyes  grow  tired, 
because  a  con- 
stant effort  must 

be  made  to  render  FlG  163  _  Snei]en's  test  letters.  These  should  be 
more  curved  the  seen  distinctly  by  a  correct  eye  at  a  distance  of 

twenty  feet, 
convex     surfaces 

of  the  crystalline  lens.  This  greater  bulging  of  the  lens 
is  necessary  to  bring  the  rays  of  light  from  a  near-by 
object  to  a  focus  on  the  retina.  The  bulging  is  produced 
by  contracting  the  ring  of  muscular  fibers,  the  ciliary 
muscle,  lying  in  the  sclerotic  coat  at  the  edge  of  the  cornea 
where  the  ligament  of  the  lens  is  fastened.  The  con- 
traction of  the  ciliary  muscle  loosens  the  ligament  which, 
when  tight,  tends  to  flatten  somewhat  the  curved  faces 
of  the  lens  (Fig.  161). 

Nearsightedness.  —  This  is  usually  due  to  the  eye  being 
longer  than  normal  from  before  backward.  The  rays  of 
light  are  brought  to  a  focus  before  they  reach  the  retina. 
Sometimes,  however,  the  eye  is  of  usual  length,  but  the 
lens  or  cornea  is  too  convex  and  therefore  focuses  the 
light  before  it  reaches  the  retina.  This  defect  is  seldom 


252  THE   SENSE    ORGANS 

present  in  children  under  four  years  of  age.  It  is  pro- 
duced in  later  years  by  pressure  of  the  muscles  on  the 
sides  of  the  eyeballs  whose  coats  have  become  weak. 
Nearsightedness  is  remedied  by  wearing  double  concave 
glasses,  which  prevent  the  rays  of  light  from  coming  to 
a  focus  too  soon. 

Farsightedness.  —  This   is   caused   either    by   the   eye 
being  shorter  than  normal  from  before  backward  or   by 


FIG.  164. —To  test  for  astigmatism.    When  looking  with  one  eye  at  either 
figure,  if  some  of  the  lines  appear  blurred,  astigmatism  is  present. 

too  little  curvature  of  the  surfaces  of  the  lens.  This  is 
an  exceedingly  common  ailment  among  persons  over 
50  years  of  age.  In  young  people  the  lens  is  soft,  and 
therefore  its  shape  is  easily  changed  by  tightening  or 
relaxing  the  ligament  enveloping  it.  The  eye  at  rest  has 
the  lens  so  shaped  as  to  focus  the  light  from  objects  a 
hundred  feet  or  more  distant.  Farsightedness  is  reme- 
died by  the  use  of  convex  glasses. 

Astigmatism.  —  This  is  a  serious  defect  in  the  eye, 
caused  by  the  unequal  curvature  of  the  surface  of  the 
cornea  or  of  the  lens.  That  is,  the  curve  of  the  line 


HOW    TO    KEEP    THE   EYES    STRONG  253 

passing  across  the  center  of  the  cornea  from  side  to  side  is 
greater  or  less  than  the  curve  of  a  line  extending  up  and 
down  across  the  center  of  the  cornea.  Headache  and  the 
smarting  of  the  eyes  after  continued  use  are  signs  of  astig- 
matism. It  may  be  remedied  by  glasses,  which  can  be 
provided  only  by  an  oculist  after  the  eyes  have  been 
carefully  measured. 

Color  Blindness.  —  One  out  of  every  20  male  persons  is 
color  blind,  while  only  one  out  of  every  200  females  is 
similarly  afflicted.  Color  blind  people  are  in  most  cases 
able  to  distinguish  all  colors  except  red  and  green  with 
their  various  shades.  No  one  who  is  color  blind  can 
become  a  railway  engineer  or  a  pilot  on  a  vessel.  Its 
cause  is  unknown,  and  it  cannot  be  cured. 

Tears.  —  The  tears,  composed  of  water  and  a  very  slight 
amount  of  salts,  are  continually  formed  by  the  lachrymal 
gland  in  the  upper  and  outer  part  of  the  orbital  cavity 
just  within  the  rim  of  the  orbit.  It  is  about  as  large 
as  a  peanut  seed.  The  tears,  which  are  for  the  pur- 
pose of  moistening  the  cornea  and  eyelids,  are  carried 
away  by  the  tear  duct.  This  leads  from  the  inner  corner 
of  the  eye  through  the  bone  into  the  nose.  Certain 
emotions  cause  the  tears  to  be  formed  so  abundantly  that 
they  overflow  and  run  down  the  cheek. 

How  to  keep  the  Eyes  Strong.  —  Examination  of  the 
children  in  one  of  the  large  city  schools  showed  that  at 
six  years  of  age  four  fifths  of  them  had  perfect  eyes,  and 
only  four  out  of  a  hundred  had  serious  defects  in  sight. 
At  eight  years  of  age  three  fourths  of  the  children  pos- 
sessed perfect  eyes,  and  eight  out  of  every  hundred  had 
some  bad  defect  in  the  eye.  At  eleven  years  of  age 


254 


THE   SENSE   ORGANS 


eleven  out  of  a  hundred  had  some  serious  eye  trouble,  and 
only  a  little  over  two  thirds  had  perfect  eyes.  These 
facts  show  that  most  people  are  born  with  good  eyes,  but 

____^     they    injure     them 

by  use  in  a  wrong 
way. 

The  book  should 
never  be  held  nearer 
to  the  eyes  than  one 
foot,  and  the  read- 
ing of  print  finer 
than  that  used  in 
this  book  should  be 
avoided  by  young 
people.  The  fine 
print  used  as  foot- 
notes and  explana- 
tions of  the  main 
text  in  many  text- 
books and  even 
physiologies  is  re- 
sponsible for  start- 
ing many  eyes  on 
the  road  to  ruin. 
Trying  to  see  in  a  dim  light  and  leaning  the  head  forward 
while  reading  cause  pressure  on  the  eyeball  and  produce 
nearsightedness.  While  using  the  eyes,  the  head  should 
be  held  erect  and  the  light  be  so  arranged  as  not  to 
come  from  in  front.  The  aching  or  smarting  of  the 
eyes,  pain  in  the  head  or  back  of  the  neck,  frowning, 
or  dizziness  indicate  that  the  eyes  are  not  in  perfect 


FIG.  165.  —  Portrait  showing  how  the  eyes  may 
be  injured. 


THE   COMMON   INJUKIES    TO   THE   EYE 


255 


working  order.  Out  of  58,948  children  whose  eyes  were 
tested  in  New  York,  17,928  were  suffering  from  defective 
vision. 

No  person  should  use  glasses  until  discomfort  is  experi- 
enced after  using  the  eyes  one  or  two  hours  in  reading 
print  as  coarse  and  clear  as  that  in  this  book.  In  seeking  a 
remedy  for  poor  sight,  one  should  consult  a  physician  and 
not  take  the  risk  of  having  the  eyes  permanently  injured 
by  purchasing  glasses  from  a  quack  doctor.  Quacks  may 
be  known  by  the 
large  advertise- 
ments they  insert 
in  newspapers  or 
magazines. 

The  Common 
Injuries  to  the 
Eye.  —  Cinders 
and  bits  of  other 
hard  substances 
often  get  beneath  the  lids  of  the  eye.  They  irritate 
the  delicate  transparent  membrane  lining  the  lids  of  the 
eye  and  passing  over  the  cornea.  By  having  the  patient 
look  downward  one  may  seize  the  edge  of  the  upper  lid 
and  turn  it  backward  over  a  rounded  match  stick.  The 
particle  of  matter  can  then  be  removed  with  a  corner  of 
a  clean  handkerchief  or  a  bit  of  absorbent  cotton  wound 
around  the  head  of  a  pin.  The  lower  lid  may  be  merely 
drawn  down  to  see  and  clean  off  the  surface. 

When  the  eyes  are  red  or  inflamed  from  any  cause, 
some  relief  may  be  had  by  bathing  them  several  times 
daily  with  a  solution  of  boracic  acid,  made  by  dissolving 


FIG.  166.  —  Method  of  turning  the    eyelid  up   to 
remove  dirt. 


256  THE   SENSE   ORGANS 

in  a  teacupful  of  water  as  much  boracic  acid  as  will  lie  on 
a  silver  half  dollar. 

Sore  eyes  are  usually  much  relieved  by  being  washed  out 
with  the  boracic  acid  solution,  because  this  tends  to  kill 
the  germs  causing  the  trouble.  Care  should  be  taken 
that  the  germs  in  the  sore  eyes  do  not  get  on  pencils, 
towels,  or  handkerchiefs  used  by  other  persons  and  thus 
make  their  eyes  sick. 

Cataract  is  a  serious  affection  which  may  produce  com- 
plete blindness.  It  is  due  to  the  crystalline  lens  becom- 
ing opaque.  The  removal  of  the  lens  and  the  use  of 
proper  glasses  often  remedy  the  difficulty. 

How  Narcotics  Affect  the  Sense  Organs.  —  The  use  of 
tobacco  daily  seems  in  some  degree  to  affect  the  sense 
organs  of  the  mouth  so  as  to  lead  to  a  desire  for  strong 
drink.  Much  chewing  and  smoking  tend  to  lessen  the 
sense  of  taste.  Hearing,  as  a  rule,  is  but  little  injured  by 
either  tobacco  or  alcohol,  though  occasionally  a  catarrh  ex- 
tending up  the  Eustachian  tube  to  the  middle  ear  may  be 
made  more  severe  in  the  young  by  the  use  of  cigarettes. 
Excessive  smoking  is  likely  to  decrease  the  keenness  of 
the  sense  of  smell,  because  the  delicate  mucous  membrane 
containing  the  olfactory  organs  is  irritated  by  tobacco 
smoke. 

It  has  been  reported  that  the  excessive  use  of  tobacco 
causes  wasting  of  the  optic  nerve  leading  from  the  eye  to 
the  brain.  Late  investigations,  however,  show  that  this 
is  probably  not  true.  Nevertheless  frequent  smoking  in 
the  young  has  been  known  to  affect  the  sight  seriously. 
Dr.  Alfred  Woodhull,  of  the  United  States  Army,  says  : 
"  Tobacco  is  liable  to  render  vision  weak  and  uncertain, 


QUESTIONS  257 

causing  objects  to  appear  nebulous,  or  it  creates  the  sensa- 
tions of  floating  spots."  One  well-known  eye  specialist 
alone  reports  35  cases  of  injured  vision  produced  by  the  con- 
tinual irritation  of  the  optic  nerve  by  tobacco.  Dr.  Mc- 
Sherry  says  when  sight  fails  in  smokers  and  no  change  in 
structure  can  be  seen,  tobacco  poisoning  may  be  assumed. 
Candidates  for  the  United  States  Naval  Academy  rejected 
on  account  of  poor  eyesight  have  in  most  cases  admitted 
using  tobacco  while  young. 

The  period  of  life  before  twenty  is  the  time  when  the 
sense  organs  are  most  markedly  affected  by  the  unwise 
use  of  tobacco  and  alcoholic  drinks.  Even  later  in  life, 
narcotics  may  do  lasting  injury  to  the  senses.  The  use 
of  much  liquor  produces  bloodshot  eyes,  because  the 
muscles  of  the  walls  of  the  arteries  are  relaxed  and  so 
become  enlarged.  Long  use  of  intoxicants  has  been 
known  to  do  permanent  injury  to  the  optic  nerve,  which 
was  probably  due  to  the  paralyzing  effect  of  the  alcohol 
on  the  nerves  controlling  the  blood  vessels  of  the  head. 

Questions 

1.  Explain  the  location  and  attachments  of  the  eyeball.  2.  How 
is  the  eyeball  moved  ?  3.  Name  the  parts  of  the  eye.  4.  Name  the 
parts  composing  the  three  coats  of  the  eyeball.  5.  Describe  the 
retina.  6.  What  is  the  color  of  your  iris  and  what  is  its  use? 
7.  Name  the  three  humors.  8.  Explain  the  nature  of  light.  9.  By 
means  of  a  drawing  show  how  the  rays  of  light  are  bent  in  passing 
through  a  lens.  10.  Describe  the  process  of  seeing.  11.  What  de- 
fects in  the  eye  cause  near  sight?  12.  How  may  near  sight  and 
far  sight  be  remedied?  13.  What  is  color  blindness?  14.  Explain 
the  formation  of  tears.  15.  Give  facts  showing  that  the  eyes  are 
more  perfect  in  children  than  in  older  ones.  16.  What  may  help 
keep  the  eyes  in  good  condition  ?  17.  How  may  particles  of  dirt  be 
DAV.  PHYS.  — 17 


258  THE   SENSE   ORGANS 

removed  from  beneath  the  eyelids  ?  18.  What  care  should  be  given 
sore  eves?  19.  What  effect  has  tobacco  on  the  sense  organs?  20.  At 
what  period  of  life  are  narcotics  liable  to  do  most  injury  to  the  sense 
organs? 

Suggestions  for  the  Teacher 

1.  Several  eyes  of  pigs  or  cows  may  be  secured  from  the  butcher. 
Note  the  attachment  of  the  several  muscles  to  the   tough    sclerotic 
coat.     In  very  cold  weather  one  or  two  eyes  should  be  left  out  over 
night  to  freeze,  or  they  may  be  frozen  in  a  few  hours  in  a  mixture  of 
cracked  ice  and  salt.     With  a  sharp  knife  cut  one  of  the  frozen  eyes 
through  the  middle  from  before  backward,  and  note  the  arrangement 
of  the  three  humors  and  coats,  and  then  place  the  eye  in  a  dish  of 
pure  formaldehyde  solution.     A  fresh  eye  should  be  cut  open  from 
side  to  side  with  a  pair  of  sharp-pointed  scissors.     Keep  the  point  of 
the  blade  near  to  the  inner  surface  of   the  eyeball.     The  vitreous 
humor  and  lens  may  be  turned  out  together,  and  when  laid  on  fine 
print,  will  show  considerable  magnifying  power.     The  retina  appears 
as  a  thin,  grayish,  very  tender  lining  of  most  of  the  eyeball.     Note  the 
black  choroid  as  thin  as  paper. 

2.  Show  with  a  magnifying  glass  or  convex  lens  of  any  kind  how 
the  rays  of  light  are  brought  to  a  focus  by  holding  the  glass  in  the 
sun  at  the  right  distance  from  a  piece  of  paper  to  show  a  spot  of  light 
as  large  as  a  pin's  head  on  the  paper. 

3.  Test  the  eyes  of  the  pupils  with  Snellen's  test  letters,  and  note 
how  close  the  pupils  hold  the  book  to  the  eyes  when  studying.     Re- 
port any  defects  to  the  parents  and  advise  that  an  oculist  be  consulted. 
Insist  that  the  pupils  maintain  the  right  position  in  reading  to  avoid 
injuring  the  eyes.     It  is  far  more  important  that  the  pupil  should 
have  perfect  eyes  and  ears  than  that  he  should  learn  his  lessons. 


XXIII.     THE   CAUSE   OF  DISEASE 


The  Work  of  Parasites.  —  Only  one  in  every  forty  per- 
sons dies  of  old  age.  About  twice  that  number  meet 
death  by  accidents,  while  disease  is  responsible  for  over 
nine  tenths  of  the  mortality  of  the  human  race.  The 
numerous  diseases 
affecting  man  may  be 
divided  into  two  classes, 
known  as  infectious  and 
non-infectious. 

The  infectious  dis- 
eases are  caused  by 
tiny  plants  or  animals, 
called  parasites,  feed- 
ing upon  the  human 
body  which  is  their 
host.  These  parasites, 
the  smaller  of  which 
are  commonly  called 
microbes  or  germs,  make  one  ill  chiefly  by  means  of  their 
poisonous  excretions.  In  Europe  and  America  60,000,000 
people  are  annually  laid  prostrate  by  infectious  diseases 
which  result  in  over  3,000,000  deaths. 

Kinds  of  Diseases.  —  Such  infectious  ailments  as  con- 
sumption, smallpox,  and  scarlet  fever  which  may  be  con- 
tracted by  breathing  in  the  germs  floating  in  the  air  are 

259 


FIG.    167.— Germs     that    cause    lockjaw. 
Photographed  through  the  microscope. 


260 


THE    CAUSE    OF   DISEASE 


called  contagious  diseases,  because  the  healthy  acquire  the 
disease  by  coming  near  where  the  sick  are  or  have  been. 

Maladies  like  yellow 
fever,  lockjaw,  and  ma- 
laria belong  to  the 
group  of  non-contagious 
diseases  for  the  reason 
that  persons  living  in 
the  same  house  and  even 
sleeping  in  the  same  bed 
with  the  sick  do  not 
become  ill  unless  a 
mosquito  or  a  sharp 
instrument  conveys  the 
germs  from  the  sick  to 
the  well. 

The  non-infectious  diseases  such  as  alcoholism,  diabetes, 
insanity,  and  cancer  are  due  to  changed  methods  of  work 
and  growth  on  the  part  of  cells  in  certain  regions  of  the 
body.     More  people  die 
from  infectious  diseases 
than     from     non-  infec- 
tious.    This  means  that 
most  ill   health  results 


FIG.  168. —Louis  Pasteur. 


M 


FIG.  1(59.  —  Glass  slip  '  g,  to  which  the  lower 
lip  was  touched  at  a-e  as  one  would 
touch  a  cup  in  drinking.  A  fourth  part 
of  the  circle  n  was  photographed  through 
the  microscope,  giving  the  picture  as 
seen  in  Figure  170. 


from  tiny  forms  of  life 
growing  within  our 
bodies. 

The    Discovery   of 
what  causes  Disease.  — 

Several  hundred  years  ago  disease  was  thought  to  be  due  to 
evil  spirits  which  took  up  their  abode  in  the  body.     Here 


THE  DISCOVERY   OF   WHAT   CAUSES  DISEASE        261 


FIG.  170. — Numerous  epithelial  cells  from 
the  mouth  left  on  the  glass  as  described 
iu  Figure  169. 


they  produced  con- 
tinuous suffering  until 
driven  out  by  various 
devices  such  as  beat- 
ing the  patient  with  a 
strap  or  giving  him 
so-called  medicine 
consisting  of  pow- 
dered human  bones. 
Although  for  fifty  years 
it  has  been  thought 
by  some  that  many 
diseases  were  due  to 
bacteria,  yet  the  fact 
that  each  of  certain  diseases  is  caused  by  a  particular  bac- 
terium was  not  clearly  proved  until  1876.  In  that  year 
Louis  Pasteur,  of  France,  showed  that  anthrax,  a  sickness 

of  cattle,  was  caused 
by  a  rodlike  plant. 
He  secured  a  few 
of  these  plants  from 
the  blood  of  a  sick 
cow,  and  planted  them 
in  broth,  where  they 
increased  rapidly  in 
number.  A  few  were 
then  injected  under 
the  skin  of  a  healthy 
cow  which  soon  after 

FIG.  171. -One  of  the  cells  like  those  shown       b  :   k        T       h  r 

in  Figure  170  left  by  the  lip  on  the  glass. 
The  200  or  more  black  hodies  are  bacteria.       blood    the  same   plants 


262 


THE   CAUSE   OF   DISEASE 


9 


FIG.  172.  —  Spot  a,  on  a  glass  slide  g, 
touched  with  the  thumb  moistened  from 
the  lips  as  in  turning  the  pages  of  a  book. 


were  found  in  vast  numbers.  Dozens  of  similar  experi- 
ments and  the  presence  of  these  particular  plants  and  no 

others  in  the  blood 
of  all  animals  with 
anthrax  have  made  it 
certain  that  the  disease 
is  caused  by  this  special 
germ.  In  a  similar 
manner  or  by  some 
other  equally  reliable 

method  it  has  been  shown  that  each  of  the  following  ail- 
ments is  produced  by  its  own  particular  kind  of  germ: 
diphtheria,  typhoid  fever,  malaria,  pneumonia,  leprosy, 
lockjaw,  hydrophobia,  influenza,  or  grippe,  erysipelas, 
and  tuberculosis. 

There  is  no  doubt 
that  measles,  scarlet 
fever,  smallpox,  and 
mumps  are  also  pro- 
duced by  germs,  but 
no  one  has  yet  been 
able  to  find  them. 
Inasmuch  as  all  infec- 
tious diseases  may  be 
prevented  by  keeping 
the  germs  out  of  the 
body,  much  effort  has 
been  made  to  learn  how 
they  gain  entrance. 

Hew  Germs  enter  the  Body.  —  The  germs  of  any  conta- 
gious disease  may  be  taken  in  by  breathing,  but  other 


FIG.  173.  — The  fourth  part  of  the  circle  in 
Figure  172,  showing  a  score  of  cells  from 
the  lips.  Photographed  through  the 
microscope. 


HOW  GERMS  ENTER  THE  BODY 


263 


FIG.  174.  —  One  of  the  cells  like  those  left  by 
the  thumb  on  the  glass  slide,  as  shown  in 
Figure  173.  The  hundred  or  more  tiny 
black  bodies  are  bacteria,  always  abun- 
dant on  the  lips.  Photographed  through 
the  microscope. 


channels  of  infection 
are  also  known.  In- 
fluenza, or  grippe, 
pneumonia,  diphtheria, 
sore  throat,  and  whoop- 
ing cough  are  no  doubt 
often  contracted  by  a 
healthy  person  drink- 
ing from  the  same  cup 
lately  used  by  those 
;  ust  recovering  from 
sickness.  Numerous 
disease  germs  as  well 
as  harmless  ones  are 
present  in  the  sputum 
of  such  patients.  By 
examining  with  the  microscope  a  glass  touched  by  the  lips, 
I  have  found  over  20,000  bacteria.  I  have  seen  more  than 
5000  germs  deposited  on  a  glass  slip  by  a  single  touch  of 

a  finger  moistened  with  saliva 
to  aid  in  turning  the  pages 
of  a  book.  The  fingers  touch- 
ing soiled  books,  clothing, 
pencils,  or  other  things  han- 
dled by  the  sick  may  convey 
the  germs  to  the  mouth.  The 
number  of  days  elapsing  from 
the  time  the  germs  enter  the 
body  to  the  time  when  the 
disease  appears  is  known  as 
the  incubation  period. 


FIG.  175.  —  Two  rlies  leediug  on 
spit  containing  millions  of  bac- 
teria, many  of  which  will  be 
carried  on  their  feet  to  the  food 
on  the  table. 


264 


THE  CAUSE   OF   DISEASE 


Non-contagious 


Slightly  contagious 


THE  CHARACTER  AND  INCUBATION  PERIOD  OF  INFECTIOUS  DISEASES 

Lockjaw 
Yellow  fever 
Hydrophobia 
Malaria 

Sleeping  sickness 
Blood  poisoning 
Dysentery 
Peritonitis 
Appendicitis 

Trichinosis 

PERIOD  OF 

INCUBATION 

IN  DATS 

Diphtheria 1-6 

Tuberculosis 20-10,000 

Typhoid  fever 8-20 

Leprosy unknown 

Pneumonia unknown 

Grippe 1-5 

Cholera 1-10 

Bubonic  plague      ....     3-12 

Scarlet  fever      t    ....     1-7 

Smallpox 8-16 

Measles 8-16 

Very  contagious    .    .    .    .    <{  Mumps 14-21 

Chicken  pox 12-16 

Whooping  cough   ....     8-16 
Typhus  fever     .....     6-12 


How  the  Germs  of  Tuberculosis  enter  the  Body.  —  Tubercu- 
losis, commonly  called  consumption,  the  most  common  of  all 
maladies,  is  generally  acquired  by  breathing  into  the  lungs 
the  germs  which  come  from  the  dried  sputum  of  persons 
having  the  disease.  It  has  lately  been  shown  that  the  germs 
may  also  reach  the  lungs  by  passing  through  the  walls  of  the 
alimentary  canal  into  the  lymph  vessels  and  thence  by  the 


THE   DAVNGER   FROM    TUBERCULOSIS   IN    COWS        265 


blood  to  the  lungs.  Here  the  thin-walled  capillaries  per- 
mit the  germs  to  pass  through  into  the  tissues.  The 
germs  once  in  the  body  may  lie  there  without  growing 
for  twenty  years. 

The"  lungs  of  ten  healthy  guinea  pigs  fed  on  milk  con- 
taining tubercle  bacilli  became  in  about  two  months  badly 
affected  with  tuber- 
culosis.  These 
germs,  injected 
under  the  skin  of 
hogs  or  cows,  in 
most  cases  produce 
disease  of  the  lungs. 
Calves  fed  on  the 
milk  of  tuberculous 
cows  only  a  few 
days  acquire  tuber- 
culosis of  the  lungs. 
The  sputum  of  tu- 
berculous patients 
contains  millions  of 
the  disease  germs. 
These  may  get  on 
the  furniture,  may 
be  carried  by  flies 
from  the  spittoon  to  food,  or  may  dry  and  be  blown 
about  in  the  wind.  In  any  case  they  are  liable  to  reach 
the  mouth  of  a  healthy  person. 

The  Danger  from  Tuberculosis  in  Cows.  —  A  large  number 
of  cows  have  tuberculosis,  but  it  is  often  not  detected  by  a 
farmer  until  the  animals  become  very  sick.  Nearly  one 


FIG.  176.  — A  dish  of  beef  broth  jelly  on  which 
a  fly  was  allowed  to  walk  for  a  few  minutes. 
Wherever  a  germ  was  rubbed  off  from  the 
fly's  feet,  it  grew  and  made  millions  of  germs, 
appearing  as  a  white  spot  the  next  day.  The 
white  spots  in  the  picture  therefore  show  how 
many  germs  that  fly  would  have  left  on  food 
over  which  it  crawled. 


266 


THE   CAUSE   OF   DISEASE 


third  of  the  cattle  of  Great  Britain  are  said  to  be  tuber- 
culous, and  investigations  show  that  there  are  not  less 
than  a  quarter  of  a  million  tuberculous  cows  east  of  the 
Mississippi  River.  Fortunately  less  than  half  of  them 
shed  the  germs  in  their  milk,  but  vast  numbers  of  the 
germs  are  found  in  their  manure.  This  often  soils  the 


Fio.  177.  —  Showing  how  disease  germs  often  reach  the  drinking  water,   c, 
cesspool ;  Im,  layer  of  rock ;  w,  wash  water. 


cow,  then    becomes    dry,  and  is  later   brushed  off   into 
the  milk  pail. 

Germs  of  tuberculosis  have  been  frequently  found  in 
milk,  and  numerous  cases  are  on  record  where  the  use  of 
milk  from  sick  cows  has  given  the  disease  to  children. 
Tuberculosis  germs  lodging  in  the  lungs  produce  con- 
sumption or  phthisis;  in  the  lymphatic  glands,  scrofula  ; 
in  the  skin,  lupus;  in  the  bone,  white  swelling^  hip-joint 
disease,  or  other  trouble ;  and  in  the  membranes  of  the 
spinal  cord  or  brain,  meningitis. 


TYPHOID   FEVER   AND   WATER 


267 


Typhoid  Fever  and  Water.  —  The  germs  of  typhoid  fever 
gain  access  to  the  body  in  most  cases  with  food  or  water. 
In  200  epidemics,  during  each  of  which  from  10  to  1300 
people  were  affected  with  the  fever,  71  per  cent  were 
caused  by  water  and  28  per  cent  by  milk.  In  the  winter 
of  1885  the  excreta  from  a 
typhoid  patient  were  cast  out 
on  the  snow  along  the  moun- 
tain stream  supplying  Plym- 
outh, Pennsylvania,  with 
water.  During  the  first  thaw 
of  spring,  the  excreta  were 
carried  with  the  melted  snow 
into  the  reservoir,  and  two 
weeks  later  numerous  cases  of 
fever  appeared  daily  in  the  town 
until  there  was  a  total  of  1104 
persons  sick.  When  an  in- 
vestigation showed  that  none 
who  had  used  water  from 
other  sources  than  the  mountain 
stream  were  affected  with  the 
fever,  there  was  no  doubt  about 
the  cause  of  the  epidemic.  Other  serious  epidemics  have 
occurred  through  the  use  of  polluted  water  as  follows  :  in 
1893-189-4  Windsor,  Vermont  had  130  cases,  Grand  Forks, 
North  Dakota  had  1245  cases,  and  Montclair,  New  Jersey 
had  108  cases;  in  1895  Stamford,  Connecticut  had  406 
cases  ;  in  1903-1904  Leadville,  Colorado  had  450  cases, 
Marshaltown,  Iowa  had  418  cases,  Butler,  Pennsylvania 
had  1364  cases,  and  Watertown.  New  York  had  600  cases. 


FIG.  178.  —  Drawing  of  a  piece 
of  deltoid  muscle  of  a  girl 
who  ate  pork  not  well  cooked, 
and  died  of  trichinosis.  Note 
the  many-coiled  trichina. 
Magnified. 


268 


THE   CAUSE   OF   DISEASE 


The  scattered  cases  of  typhoid  occurring  in  nearly  all 
communities  may  be  due  to  a  very  slight  pollution  of  the 
water,  to  flies  carrying  the  germs  from  human  excreta  to 
food,  or  to  eating  raw  oysters,  lettuce,  and  celery,  in  or 
upon  which  the  germs  may  lodge. 

Typhoid  Fever  transmitted  by  Milk.  —  Many  severe  epi- 
demics of  fever  have  resulted  from  infected  milk.  As 

the  cows  never  suffer 
from  this  malady,  it  is 
evident  that  the  germs 
must  get  into  the  milk 
from  an  outside  source. 
This  source  is  often 
the  water  used  from  a 
polluted  well  or  stream 
to  wash  the  cans.  A 
single  germ  remaining 
in  the  water,  clinging 
to  the  can,  is  capable  of 
developing  so  rapidly 
in  milk  as  to  give  rise 
to  over  1,000,000  germs  in  12  hours.  Frequently  germs 
have  been  known  to  get  into  the  milk  from  the  hands  or 
clothes  of  those  who  have  just  recovered  from  the  disease, 
or  from  those  who  have  been  nursing  a  typhoid  patient. 

Infectious  but  not  Contagious  Diseases.  —  The  germs  of 
lockjaw  live  in  the  soil  and  get  into  a  wound  with  dirt. 
Hydrophobia  is  caused  by  the  bite  of  rabid  cats  or  dogs 
with  the  germs  of  this  disease  in  their  saliva.  Trichina 
are  tiny  worms  sometimes  found  in  pork,  which  if  not  well 
cooked  may  cause  sickness.  Yellow  fever  and  malaria  are 


FIG.  179.  —  Two  malarial  germs,  each  in  a 
blood  corpuscle.    Magnified. 


ALCOHOL   AND    DISEASE 


269 


caused  by  germs  put  into  the  blood  by  the  bite  of  mos- 
quitoes. Only  one  kind  can  transmit  the  yellow  fever. 
The  few  kinds  of  mosquitoes  bearing  malaria  germs  can 
be  recognized  by  their  oblique  position  in  standing. 

The  Hookworm  Disease.  - 
This  is  common  among  the 
people  of  the  South.  It  is 
caused  by  tiny  worms  suck- 
ing blood  from  the  lining  of 
the  intestine  and  giving  off 
poison.  This  makes  the  per"- 
son  feel  weak  and  lazy,  and 
may  cause  death.  The  eggs 
of  the  worms  pass  out  with 
the  bowel  excretions  and  hatch 
into  tiny  young  which  may 
crawl  to  the  well  or  spring 
and  so  reach  another  person. 
They  often  spread  through  the 
soil  and  enter  the  body  by  bor- 
ing throngh  the  skin  of  those 
going  barefooted,  causing  "  dew 
itch"  or  "ground  itch." 

Alcohol  and  Disease.  —  The 
continual  use  of  liquor  weakens 
the  cells  of  the  body  which 

naturally  kill  off  the  harmful  germs.  Late  investigations 
clearly  show  that  those  consuming  alcoholic  drinks,  except 
in  very  small  quantities,  are  not  only  attacked  sooner  than 
others  by  infectious  diseases,  but  are  also  less  able  to  resist 
the  effects  of  the  disease.  The  greatest  Russian  scientist 


FIG.  180.  —  Position  taken  by  a 
common  mosquito  (Culex)  a, 
and  by  a  malaria  mosquito 
(Anopheles)  b,  when  alighting. 
Note  that  in  the  malaria  mos- 
quito the  two  palpi  just  below 
the  sucking  bill  are  about 
four  times  as  long  as  in  the 
common  mosquito.  After 
Howard. 


270 


THE   CAUSE   OF   DISEASE 


has  lately  said  that  alcohol  paralyzes  those  elements  in  the 
body  tending  to  prevent  disease.  By  experimenting  he 
found  that  in  exposing  rabbits  to  certain  disease  germs 
only  those  animals  which  had  been  given  alcohol  ever 

contracted    the 
disease. 

Constant  users 
of  alcoholic  drinks 
are  especially  lia- 
ble to  fall  a  prey 
to  diseases  of  the 
respiratory  sys- 
tem. Alcohol  so 
weakens  the  body 
cells  which  ordi- 
narily destroy  the 
germs  of  pneu- 
monia that  the 
disease  is  often 
able  to  gain  a 
hold  in  the  sys- 
tems of  drinkers. 
The  enlargement 
of  the  blood  vessels  of  the  lungs  produced  by  the  stupe- 
fying effect  of  the  alcohol  increases  the  tendency  to 
inflammation. 

Indulgence  in  the  use  of  beer,  wine,  and  whisky  is  con- 
sidered to  have  such  a  serious  effect  on  the  tissues  of  the 
body  that  The  International  Congress  of  Tuberculosis  in 
1905  passed  the  following  resolution  :  "  In  view  of  the 
close  connection  between  alcoholism  and  tuberculosis,  this 


FIG.  181. — Well,  w,  containing  very  impure  water 
causing  intestinal  sickness.  Analysis  of  the 
water  showed  many  germs  indicating  that  it  was 
dangerous  for  use. 


SUGGESTIONS   FOB   THE  TEACHER 

Congress  emphasizes  the  importance  of  combining  the 
fight  against  tuberculosis  with  the  struggle  against  alco- 
holism." 

Diseases  of  the  liver,  kidneys,  blood  vessels,  and  heart 
often  result  from  the  long-continued  use  of  beer  or 

whisky. 

Questions 

1.  Of  every  hundred  deaths  how  many  result  from  disease? 
2.  What  is  the  cause  of  infectious  diseases  ?  3.  Give  facts  showing 
that  infectious  diseases  result  in  much  sickness.  4.  What  is  a  conta- 
gious disease?  5.  Name  some  contagious  diseases.  6.  Name  some 
infectious  diseases  not  contagious.  7.  How  has  it  been  shown  that  a 
special  germ  causes  a  special  disease  ?  8.  Name  ten  diseases  caused  by 
germs.  9.  How  may  diphtheria,  sore  throat,  whooping  cough,  and 
grippe  be  contracted  ?  10.  How  may  the  germs  of  some  diseases  be 
transferred  to  the  leaves  of  a  book?  11.  Explain  the  incubation  period 
of  disease.  12.  Name  three  diseases  with  short  incubation  periods. 
13.  Name  two  diseases  with  long  incubation  periods.  14.  Name  four 
very  contagious  diseases.  15.  How  do  the  germs  of  tuberculosis  enter 
the  body?  16.  What  facts -show  that  the  germs  of  tuberculosis  get- 
ting into  the  blood  are  most  likely  to  lodge  in  the  lungs?  17.  How 
do  germs  of  tuberculosis  get  into  milk?  18.  What  diseases  are 
caused  by  the  germs  of  tuberculosis?  19.  How  do  the  germs  of 
typhoid  fever  enter  the  body?  20.  Give  facts  showing  that  typhoid 
fever  is  generally  acquired  by  drinking  impure  water.  21.  How 
may  flies  be  the  means  of  causing  typhoid  fever?  22.  How  is  it  pos- 
sible for  milk  to  be  the  source  of  typhoid  fever?  23.  What  cause 
lockjaw  and  hydrophobia?  24.  How  do  the  germs  of  malaria  enter 
the  system  ?  25.  Give  evidence  showing  that  alcohol  is  a  factor  in 
producing  disease. 

Suggestions  for  the  Teacher 

Bulletins  or  pamphlets  published  by  the  State  Board  of  Health 
should  be  distributed  among  the  pupils  and  each  one  asked  to  write 
on  one  or  two  sheets  of  paper  what  he  considers  the  most  important 
things  to  be  remembered  in  the  bulletins.  These  bulletins  may  be  had 
free  in  most  states  by  requesting  them  from  the  State  Board  of  Health 
at  the  capital  of  the  state. 


XXIV.     THE  PREVENTION  OF  DISEASE 


Tuberculosis 


The  General  Methods.  — There  are  three  general  methods 
of  preventing  infectious  disease.  One  way  is  to  destroy 
the  harmful  germs  continually  passing  out  of  the  sick 
body  with  the  excretions,  and  so  prevent  them  from  reach- 
ing the  healthy.  A  second  plan  is  to  stop  the  disease 
germs  scattered  about  by  careless  people  from  entering  the 

body.  A  third 
means  of  keeping 
away  disease  is  to 
develop  in  the  body 
tissues  a  substance 
which  has  the 
power  to  destroy 
certain  disease 
germs  entering  the 
system. 

Destroying      the 
Cause   of   Disease. 

—  Until  1890  but  little  attention  was  given  to  the 
scientific  prevention  of  disease.  A  sure  method  of  re- 
straining criminals  from  robbing  and  killing,  is  to  keep 
them  shut  up  in  prisons  or  to  kill  them.  Likewise,  a 
certain  method  of  preventing  harmful  germs  from  robbing 
some  citizens  of  health  and  killing  others  is  to  destroy 
the  germs  when  they  escape  from  the  body  of  the  sick. 

272 


JHphthena  <•  Typhoid 


Pneumonia 


FIG.  182. — Diagram  of  a  part  of  our  nation's 
cemetery.  The  black  dots  represent  the  num- 
ber of  graves  made  daily  for  persons  dying  of 
the  four  diseases. 


DESTROYING   THE   CAUSE   OF   DISEASE 


273 


The  bowel  and  kidney  excretions  of  a  person  suffering 
from  any  of  the  contagious  diseases  should  always  be 
treated  in  a  way  to  kill  the  germs.  This  may  be  done  by 
adding  to  them  four  times  the  quantity  of  boiling  water. 
The  easiest  and  surest  method  of  killing  the  germs  is  to 
add  to  the  excretions  an  equal  amount  of  formalin,  made 
by  mixing  a  teacupful  of  formaldehyde  solution  with  a 
gallon  of  water.  After  adding  the 
germ  killers,  called  disinfectants, 
the  material  should  stand  a  half 
hour  before  being  disposed  of  in 
the  usual  way. 

Nearly  300,000  cases  of  typhoid 
fever  occur  annually  in  this  coun- 
try, resulting  in  about  40,000 
deaths.  Careful  investigations 
have  shown  that  three  fourths  of 
this  suffering  and  loss  of  life  was 
due  to  negligence  in  permitting 
the  living  typhoid  germs  in  the 
kidney  and  bowel  excreta  of  the  sick  to  escape  into  the 
streams,  wells,  and  soil.  The  soil  about  many  homes  and 
schools  in  the  South  contains  thousands  of  hookworms 
hatched  from  the  eggs  in  the  bowel  waste  allowed  to  touch 
the  ground.  These  worms  will  pierce  the  skin  of  bare- 
footed children  and  travel  through  the  blood,  lungs,  and 
windpipe  to  suck  the  blood  in  the  intestine.  Where  there 
is  no  sewer  connection,  tight  tubs  or  cement  tanks  should 
be  used  for  the  body  waste.  It  is  wise  to  avoid  going 
barefooted. 

It  should  be  remembered  that  the  disease  germs  often 

DAV.    PHTS.  — 18 


FIG.  183.  —  A  receptacle 
frequently  receiving  the 
germs  of  grippe,  tuber- 
culosis, tonsilitis,  and 
diphtheria  to  be  distrib- 
uted by  flies. 


274  THE   PREVENTION    OF    DISEASE 

continue  in  the  excretions  of  the  sick  a  week  or  more 
after  recovery.  Failure  to  kill  the  germs  in  the  ex- 
creta of  a  single  patient  at  Plymouth,  Pennsylvania, 
resulted  in  1104  cases  of  typhoid  fever  and  many  deaths. 
The  sputum  from  the  sick  should  be  received  on  pieces  of 
cloth  or  in  well-greased  pasteboard  boxes  covered  to  pre- 
vent the  entrance  of  flies.  The  cloths  or  boxes  should  be 
burned  at  the  end  of  each  day.  Flies  are  known  to 
distribute  the  bacteria  of  consumption  and  typhoid 
fever. 

The  Isolation  of  the  Sick.  —  A  person  suffering  from  a 
contagious  disease  should  in  most. cases  be  quarantined. 
To  quarantine  means  to  isolate  or  to  separate  the  sick 
from  the  well.  The  patient  should  be  placed  in  a  large 
airy  room  shut  off  from  the  rest  of  the  house  as  much  as 
possible  and  exposed  to  the  sun,  nature's  germ  killer. 
The  hangings  and  carpets  and  all  unnecessary  furniture 
should  be  removed.  Only  the  nurse  and  doctor  are  to  be 
allowed  to  enter  the  room,  and  no  clothing,  dishes,  or 
other  articles  should  be  taken  from  the  room  without 
being  soaked  in  boiling  water. 

Disinfection  of  the  Room.  —  Disinfection  means  the  kill- 
ing of  the  agents  producing  disease.  An  antiseptic  is  a 
substance  which  merely  restrains  the  germs  from  growing. 
Ice,  vaseline,  a  one-per-cent  solution  of  carbolic  acid,  and 
a  weak  solution  of  boracic  acid  are  common  antiseptics. 
The  three  best  disinfectants  are  a  five-per-cent  solution  of 
carbolic  acid,  sunlight,  and  formaldehyde  solution. 

During  the  patient's  sickness  the  room  should  not  be 
swept,  but  wiped  up  daily  with  a  cloth  wrung  out  of  a 
quart  of  water  to  which  ha-ve  been  added  two  or  three 


DISINFECTION    OF   THE   PERSON 


275 


tablespoonfuls  of  formaldehyde  solution.  When  the  pa- 
tient has  recovered,  the  room  should  be  disinfected  by 
closing  it  tightly,  inserting  wet  paper  in  cracks  and  key- 
holes, and  evaporating,  by  heating  on  an  oil  stove,  two 
quarts  of  water  to  which  has  been  added  a  pint  of  pure 
formaldehyde  solution.  In  the  absence  of  a  stove  the 
liquid  may  be  sprinkled 
on  the  floor  and  bed- 
ding, but  the  results 
are  not  so  good.  The 
room  should  remain 
closed  twelve  hours, 
and  then  be  exposed 
to  sunshine  and  fresh 
air  a  day  or  two. 

Disinfection  of  the 
Person.  —  After  touch- 
ing a  patient  or  han- 
dling his  clothing,  the 
hands  should  be  thor- 
oughly washed  with 
soap  and  water.  The 
clothing  used  about  the 
sick  must  be  boiled 
before  it  is  safe.  Toys  handled  by  a  scarlet  fever  patient 
have  been  known  to  give  the  disease  to  others  more 
than  a  year  later.  When  the  patient  has  recovered, 
his  entire  body,  including  the  hair,  should  be  carefully 
washed  with  water  and  plenty  of  soap.  The  outer 
•clothes  of  the  nurse  should  also  be  boiled,  and  in  the 
znore  contagious  diseases  the  hair  thoroughly  washed. 


FIG.  184.  —  Why  a  sick  room  should  not  be 
swept.  A  dish  of  beef  broth  jelly  was 
left  open  for  two  minutes  in  a  room  that 
was  being  swept.  Wherever  a  germ  fell 
it  grew  and  produced  millions  forming  a 
white  spot.  Therefore  the  white  spots 
show  how  many  germs  fell  on  a  circle  two 
inches  in  diameter. 


276 


THE   PREVENTION   OF   DISEASE 


I 


Keeping  the  Germs  out  of  the  Body.  —  With  great  care 
it  is  possible  to  keep  out  of  the  body  the  agents  causing 
at  least  five  of  the  infectious  diseases.  The  germs  re- 
sponsible for  diarrhea,  dysentery,  cholera  infantum,  and 
typhoid  fever  may  generally  be  avoided  by  keeping  flies 

away  from  food,  and 
by  drinking  from  clean 
vessels  water  or  milk 
known  to  be  pure,  or 
by  heating  these  fluids 
up  to  the  boiling  point. 
It  is  better  to  pas- 
teurize the  milk,  as 
described  in  Chapter 
VII.  The  use  of 
boiled  drinking  water 
in  Philadelphia,  Cin- 
cinnati, Cleveland, 
Louisville,  Memphis, 
New  Orleans,  St. 
Louis,  and  Washing- 
ton during  the  years 
1900-1904  would  have  prevented  50,000  cases  of  typhoid 
fever.  The  use  of  boiled  water  in  Pittsburg  during  the 
same  five  years  would  have  prevented  10,000  cases  of 
fever  in  that  city. 

The  germs  of  malaria  and  yellow  fever  are  easily  ex- 
cluded from  the  system  by  preventing  the  two  kinds  of 
mosquitoes  carrying  them  from  biting.  As  the  young  of 
these  insects  live  only  in  quiet  pools  of  water  with  no  fish, 
their  numbers  may  be  much  lessened  by  draining  the 


FIG.  183.  —  Wigglers,  the  young  of  mosqui- 
toes, trying  to  breathe  through  their  air 
tubes  sticking  out  on  the  surface  of  the 
water  covered  with  oil. 


KEEPING  THE  GEKMS  OUT  OF  THE  BODY 


277 


puddles  and  pouring  out  the  water  in  tubs  and  old  cans. 
Where  this  cannot  be  done  the  young  may  be  killed  by 
kerosene  poured  on  the  water,  using  one  pint  for  every 
hundred  square  feet  of  surface. 


b  a 

Lawrence,  Mass. 


b  a 

Albany,  N.Y. 


6  a 

Binghamton,  N.Y. 


b  a 

Watertown,  X.Y. 


FIG.  186.  —  Diagram  showing  how  supplying  a  city  with  good  water  lessens 
the  sickness  and  death.  The  lines  b  above  each  city  show  the  relative  num- 
ber of  persons  dying  of  typhoid  fever  before  the  water  was  filtered.  The 
lines  a  show  the  number  dying  of  typhoid  after  the  water  was  filtered.  The 
figures  are  the  number  of  typhoid  deaths  occurring  annually  out  of  every 
100,000  inhabitants. 

The  terrible  bubonic  plague,  or  black  death,  is  also  con- 
veyed to  man  by  the  bite  of  a  flea  living  on  rats  and 
man.  Leprosy  may  be  transmitted  by  the  bite  of  bedbugs 
or  fleas. 

When  near  patients  with  typhus  feVer,  scarlet  fever, 
smallpox,  grippe,  measles,  mumps,  and  chicken  pox  there 


278 


THE   PREVENTION   OF   DISEASE 


is  no  way  of  shutting  the  germs  out  of  the  system, 
because  they  become  mingled  with  the  air.  The  germs 
of  diphtheria  and  tuberculosis  are  also  likely  to  mingle 
with,  the  air  and  enter  the  body  of  the  healthy  unless  the 
patients  use  great  care.  The  secretions  of  the  mouth 
and  nose  should  always  be  received  into  a  cloth  or  special 
pasteboard  cup  and  burned,  and  a  cloth,  to  be  later  burned, 
should  be  held  over  the  mouth  while  coughing.  In  quiet 
breathing  no  germs  of  any  kind  are  given  off. 

Importance  of  Filtered  Water.  —  Many  cities  getting 
their  water  from  streams  likely  to  contain  disease  germs 
pass  the  water  through  a  layer  of  sand  and  coarse  gravel 
to  remove  the  germs.  Most  sand  niters  remove  about 
ninety-eight  per  cent  of  the  germs  in  the  water.  The 
small  house  niters,  made  of  specially  prepared  material, 
take  out  all  germs,  but  must  be  cleaned  daily  and  boiled 
weekly  to  be  effective, 

TABLE  SHOWING  THE  SAVING  OF  LIFE  AT  ALBANY  BY  USE  OP 
FILTRATION  COMPARED  WITH  TROY  WHERE  DURING  THE  SAME 
PERIOD  THE  WATER  WAS  NOT  FILTERED 


Death  rate  per 

Before  filtration 

After  filtration 

100,000  in  Albany,  N.  Y. 

1894-1898 

1900-1904 

Typhoid  fever        .     .     .     . 

104 

26 

Diarrheal  diseases       .     .     . 

125 

53 

Children  under  5  yrs.      .     . 

606 

309 

Death  rate  per 

Water  not  filtered 

.  Water  not  filtered 

100,000  in  Troy,  N.T. 

1894-1898 

1900-1904 

Typhoid  fever        .... 

57 

57 

Diarrheal  diseases      .     .     . 

116 

102 

Children  tinder  5  yrs.      .     . 

531 

435 

THE  POWER  OF  THE  TISSUES  TO  KILL   GERMS       279 


Since  the  city  filter  has  been  in  use  at  Albany,  New  York, 
only  one  fourth  as  many  deaths  occur  from  typhoid  fever 
as  previously,  and  less  than  half  as  many  deaths  from 
diarrhea!  diseases. 

Sewage  Disposal.  —  The  liquid  waste  resulting  from 
housekeeping  or  manufacturing  processes  is  named  sew- 
age. This  should 
never  be  permitted 
to  run  direct  into  a 
stream  because  of  the 
germs  and  poisons  it 
may  contain.  Such 
germs  as  those  of  ty- 
phoid fever  have  been 
known  to  cause  dozens 
of  cases  of  sickness  and 
death  after  being  car- 
ried a  week  in  the  water. 
The  sewage  should  be 
passed  through  a 
storage  tank  and 
oxidizing  filter. 

In  the  country  or  village,  or  when  camping,  gal- 
vanized iron  cans  should  be  used  for  the  excretions 
from  the  body.  A  pint  of  dry  earth  thrown  into  the 
can  daily  will  prevent  odor  and  help  change  the  waste 
matter  to  mineral  earth.  When  the  can  is  full  the 
contents  should  be  buried  in  a  shallow  hole  in  the 
garden  or  field. 

The  Power  of  the  Tissues  to  kill  Germs.  —  There  is  no 
doubt  that  disease  germs  get  into  the  mouth  and  nose 


FIG.  187.  —  The  germs  causing  pneumonia 
are  the  small  oval  bacteria  usually  in 
pairs.  Photographed  through  the  micro- 
scope magnifying  1000  diameters. 


280 


THE   PREVENTION   OF   DISEASE 


every  day.  The  bacteria  causing  sore  throat  and  pneu- 
monia have  been  frequently  found  in  the  mouth  and 
throat  of  healthy  people.  These  germs  can  provoke 
disease  only  when  one  becomes  chilled  so  that  his  body 
cells  are  weakened  and  permit  the  intruders  to  get  a  start. 
In  health  the  nasal  mucus,  gastric  juice,  and  other  se- 
cretions destroy  thousands  of  germs  daily.  The  body 


FIG.  188.  —  A  healthful   bedchamber  for   clear  summer  nights  whereby  the 
germ-killing  power  of  the  blood  may  be  greatly  increased. 


cells  manufacture  and  turn  into  the  blood  and  other  se- 
cretions of  the  body  a  substance  capable  of  dissolving  bac- 
teria. There  are  also  other  agents  in  the  blood  called 
opsonins  which  affect  the  bacteria  so  that  the  white  blood 
corpuscles  are  able  to  swallow  them.  This  power  of  the 
blood  and  other  secretions  to  kill  germs  varies  in  dif- 
ferent persons,  and  also  may  be  greater  at  one  time  than 
another  in  the  same  person.  In  adults  this  power  to 
destroy'  the  germs  of  scarlet  fever  and  diphtheria  is  so 


HOW    THE    BODY    BECOMES    SAFE 


281 


great  that  healthy  persons  over  30  years  of  age  seldom 
take  these  diseases. 

Alcohol  and  the  White  Blood  Corpuscles.  —  It  has  for 
a  long  time  been  known  that  habitual  drinkers  when 
exposed  to  a  contagious  disease  are  much  more  likely  to 
become  ill  than  the  total  abstainers.  The  reason  for  this 
was  not  clearly  under- 
stood until  1906,  when 
it  was  found  that  the 
white  blood  corpuscles, 
which  destroy  disease 
germs,  are  stupefied 
by  alcohol  and  thus 
prevented  from  doing 
their  work. 

How  the  Body  be- 
comes Safe  from  Some 
Diseases.  — In  case 
disease  germs  reaching 
an  individual  have  no 
effect  on  him,  he  is 
said  to  be  immune  to  that  disease.  This  immunity,  or 
safety,  depends  upon  the  germ-killing  power  of  the 
body  fluids.  This  power  may  be  developed  in  two 
different  ways,  one  of  which  is  known  as  the  natural 
method,  while  the  other  is  the  artificial  method.  The 
natural  method  consists  in  the  use  of  an  abundance  of 
nutritious  food  well  chewed,  plenty  of  sleep,  fresh  air 
night  and  day,  arid  an  hour  of  daily  exercise.  This  is 
the  most  successful  method  of  preventing  tuberculosis 
and  colds.  The  artificial  method  is  by  the  use  of  anti- 


FIG.  189.  —  Germs  of  tuberculosis  from  the 
spit  of  a  consumptive.  Photographed 
through  the  microscope. 


282  THE   PREVENTION   OF    DISEASE 

toxins  and  vaccines  secured  from  the  domestic  animals. 
Diphtheria,  smallpox,  lockjaw,  and  hydrophobia  may 
always  be  prevented  by  this  method  if  used  in  time. 

Tuberculosis.  —  The  tiny  plants  causing  this  disease  are 
so  abundant  everywhere  that  it  is  impossible  for  those 
living  in  towns  and  cities  to  keep  them  out  of  the  system. 
More  than  half  of  the  people  over  25  years  of  age  have  at 
some  time  had  growing  in  their  tissues  the  'bacillus  tuber- 
culosis. The  examination  of  a  large  number  of  bodies  after 
death  showed  that  96  per  cent  of  those  between  the  ages  of 
18  and  30  had  been  infected  with  the  germs  ;  50  per  cent  of 
those  between  the  ages  of  14  and  18  ;  33  per  cent  of  those 
between  the  ages  of  5  and  14  ;  and  17  per  cent  of  those  be- 
tween the  ages  of  1  and  5  years.  In  most  of  these  persons, 
the  germs  had  not  multiplied  sufficiently  to  cause  any  dis- 
comfort, because  the  germ-killing  power  of  the  body  fluids 
had  kept  them  in  check.  The  fact  that  400  people  are 
dying  daily  in  the  United  States  from  this  one  disease 
and  that  one  third  of  all  deaths  occurring  between  the 
ages  of  15  and  45  years  result  from  tuberculosis  shows 
the  importance  of  trying  to  render  the  body  immune. 

Making  the  Body  Safe  from  Tuberculosis.  —  Proper 
living  will  in  99  p^r  cent  of  all  well  persons  render  the 
body  capable  of  killing  the  germs  of  tuberculosis.  The 
living  or  working  rooms  should  be  well  ventilated,  and 
the  area  of  the  open  windows  in  the  bedroom  occupied  by 
two  should  not  be  less  than  ten  square  feet  in  winter  and 
twice  as  large  in  summer.  Good  food,  including  plenty 
of  milk  and  eggs,  should  be  taken.  Exercise,  especially 
such  as  calls  into  action  the  chest  muscles  and  fills  the 
lungs  full  of  air,  ought  to  be  indulged  in  a  half  hour  or 


MAKING   THE   BODY   SAFE   FROM  TUBERCULOSIS      283 

more  twice  daily.  Eight  hours  of  sleep  with  an  extra  nap 
after  the  midday  meal  are  necessary.  There  should  be 
no  indulgence  in  alcoholic  drinks. 

Evidence  that  living  according  to  the  above  plan  will 
render  one  practically  safe  from  tuberculosis  is  furnished 


FIG.  I '.10.  —  Sleeping  quarters  in  the  foreground  at  the  sanatorium  for  con- 
sumptives at  White  Haven.  Note  that  the  rooms  are  wide  open  to  the 
fresh  air  on  three  sides.  Hundreds  of  patients  have  been  cured  here. 

from  three  sources.  Not  one  of  those  who  follow  these 
rules  of  life  suffer  from  the  disease.  Three  fourths  of 
the  half  million  persons  with  the  disease  in  this  country 
have  been  overworked  or  underfed  or  lived  in  poorly  ven- 
tilated rooms  with  sunshine  shut  out.  After  the  disease  is 
once  established  in  the  body,  living  according  to  the  above 
rules  cures  more  than  half  of  all  those  who  continue  the 
hygienic  life,  while  very  few  of  those  who  seek  help  from 
medicine  and  follow  the  ordinary  mode  of  living  recover. 


284 


THE    PREVENTION    OF   DISEASE 


How  to  cure  Consumption.  —  A  pain  in  the  chest,  a 
hacking  cough,  especially  in  the  morning,  loss  in  weight, 
and  an  evening  temperature  of  about  100  degrees  or  more 
are  strong  evidences  of  consumption  if  they  continue  a 
month  or  more.  A  physician  should  be  consulted.  Long 
experience  has  shown  that  patent  medicines  are  of  no  use 
whatever  for  the  consumptive.  Some  may  seem  to  help 

for  a  time  because 

of  the  alcohol  or 
other  tonic  they 
contain,  but  the 
help  is  only  tem- 
porary, and  many 
of  them  hasten  the 
progress  of  the 
disease.  Scientists 
agree  that  the  use 
of  any  alcoholic 
drink  advertised  to 
cure  consumption 
only  makes  it  worse,  because  the  alcohol  has  been  shown 
to  weaken  the  germ-killing  power  of  the  blood. 

The  one  treatment  which  has  been  tried  by  over  100,000 
patients  and  found  most  successful,  is  living  a  hygienic 
life  to  increase  the  germ-killing  power  of  the  blood. 
Keeping  in  the  fresh  air  by  day  and  by  night,  drinking 
daily  a  quart  or  more  of  rich  milk  containing  a  half  dozen 
raw  beaten  eggs,  in  addition  to  eating  three  nutritious 
meals,  and  exercising  according  to  strength  has  cured 
fifty-five  per  cent  of  the  tubercular  patients  taking  the 
treatment  in  the  early  stages  of  the  disease. 


FIG.  191.  —  Open  shed  facing  southward  where 
the  consumptive  patients  breathe  pure  air  all 
day. 


MIHHOD    OF    MAKING    THE    BODY    IMMUNE 


285 


The  Danger  from  a  Consumptive. — If  proper  care  is 
taken,  there  is  but  little  probability  of  contracting  con- 
sumption from  living  in  the  same  house  with  a  patient. 
No  germs  are  given  off  in  the  ordinary  breathing,  and  in 
coughing,  a  cloth 
to  be  later  burned, 
should  be  held 
before  the  mouth. 
The  sputum  must 
be  received  into  a 
paraffined  paper 
cup  with  a  cover 
to  keep  out  the 
flies  and  burned 
at  the  end  of  the 
day.  More  than 
10,000,000  germs 
are  known  to  be 
given  off  daily  by 
some  patients. 
The  drinking  cup 
and  other  table 
ware  should  be 


FIG.  192.  —  Showing  why  open  spittoons  should 
not  be  used  by  consumptives  or  any  other 
persons. 


scalded  immedi- 
ately after  use.  Observing  these  precautions  and  living 
a  more  hygienic  life  has  decreased  the  yearly  deaths  from 
tuberculosis  in  this  country  one  fourth  during  the  last 
fifteen  years. 

Artificial  Method  of  Making  the  Body  Immune.  —  Safety 
from  certain  diseases  is  acquired  by  inoculation  with 
antitoxins  or  vaccines.  Inoculation  means  injecting  a 


286 


THE   PREVENTION    OF   DISEASE 


substance  under  the  skin.  In  1880  Pasteur  discovered 
that  when  a  healthy  chicken  was  inoculated  with  cholera 
germs  weakened  by  exposure  to  the  air,  the  bird  became 
only  slightly  ill  instead  of  dying,  as  was  the  case  when 
fresh  germs  were  used.  When  the  same  bird  was  inocu- 
lated later  with  strong 
germs,  no  sickness 
whatever  resulted,  be- 
cause the  growth  of 
weak  germs  had  given 
the  body  tissues  time 
to  produce  a  substance 
destroying  the  cholera 
germs.  This  process 
of  rendering  a  person 
immune  to  a  severe 
form  of  a  disease  by 
inoculating  him  with 
weak  germs  is  known 
as  vaccination. 

Millions   of   dollars' 

193.  —Edwin  Jenner,  whose  discovery 
of  the  method  of  vaccination  has  pre-        Worth    of     Cattle    have 
vented  millions  from  suffering  from  the        been    gaved    b       yacci_ 
loathsome  disease  of  smallpox. 

nating    them     against 

anthrax.     Since  1904  vaccination  of  calves  against  tuber- 
culosis has  been  tried  with  great  success. 

Vaccination  for  Smallpox.  —  About  the  year  1800  Jen- 
ner, of  England,  discovered  a  method  of  preventing  small- 
pox by  inoculating  a  person  with  the  germs  of  cowpox. 
The  cowpox  germs  are  the  human  smallpox  germs  after 
they  have  become  weakened  by  being  grown  in  the 


VACCINATION    FOR   SMALLPOX  287 

tissues  of  the  cow.  Prior  to  the  practice  of  vaccination, 
smallpox  was  the  worst  of  human  maladies.  Scarcely 
any  one  lived  beyond  the  age  of  thirty  years  without  be- 
ing attacked  by  the  disease,  and  one  in  every  seven  who 
suffered  from  it  died,  while  many  others  were  made  deaf 
or  blind.  Macaulay  describes  its  ravages  in  the  follow- 
ing words:  "That  disease  over  which  science  has  since 
achieved  a  succession  of  glorious  and  beneficent  victories 
was  then  the  most  terrible  of  all  the  ministers  of  death. 
The  havoc  of  the  plague  had  been  far  more  rapid  ;  but  the 
plague  had  visited  our  shores  only  once  or  twice  in  living 
memory ;  and  the  smallpox  was  always  present,  filling  the 
churchyard  with  corpses,  tormenting  with  constant  fears 
all  whom  it  had  not  yet  stricken,  and  leaving  on  those 
whose  lives  it  spared  the  hideous  traces  of  its  power." 
In  1721  more  than  half  of  the  inhabitants  of  Boston  had 
the  disease,  and  a  few  years  later  18,000  of  the  50,000 
residents  of  Greenland  died  of  this  terrible  malady.  It 
killed  60,000,000  inhabitants  of  Europe  in  the  eighteenth 
century. 

During  the  years  1874-1894  Austria,  because  it 
did  not  compel  its  people  to  be  vaccinated,  lost  239,800 
of  its  citizens  by  smallpox.  During  the  same  years 
Prussia  compelled  vaccination,  and  lost  only  8500  by 
smallpox. 

To-day  smallpox  is  a  rare  disease,  because  vaccination 
properly  performed  absolutely  prevents  it.  In  the  small- 
pox epidemic  of  1902  in  Philadelphia  none  of  the  50 
vaccinated  nurses  caring  for  the  smallpox  patients  took 
the  disease.  In  Germany,  where  the  law  compels  every 
person  to  be  vaccinated  twice,  the  deaths  from  smallpox 


288 


THE  PREVENTION   OF   DISEASE 


are  only  one  twentieth  as  great  in  proportion  to  the  popu- 
lation as  they  are  in  the  United  States.  Every  one,  unless 
in  ill  health,  should  be  vaccinated  in  infancy  and  again  in 
the  twelfth  year  or  oftener  if  near  a  case  of  smallpox. 

Hydrophobia,  likely  to  develop  from  the  bite  of  a  rabid 
dog,  may  be  prevented  by  taking  the  Pasteur  treatment, 

which  consists  in 
several  vaccinations 
with  weak  hydropho- 
bia germs. 

Antitoxins.  —  Other 
means  of  preventing 
some  diseases  or  cur- 
ing them  are  by  using 
antitoxins  secured 
from  the  blood  of 
domestic  animals. 
Diphtheria  antitoxin 


FlG.  194.  —  Germs  of  diphtheria.     Photo- 
graphed through  the  microscope. 


is  secured  from  the 
horse  by  inoculating 
a  day  or  more  with 


it  several  times  at  intervals  of 
some  broth  in  which  diphtheria  germs  have  been  grow- 
ing and  have  given  off  their  poisons,  called  toxins. 
Before  the  broth  is  used  the  germs  are  removed  by  a 
filter.  Each  successive  dose  given  the  horse  is  in- 
creased, -and  to  overcome  these  constantly  larger  quan- 
tities of  poison,  it  develops  in  its  tissues  a  substance 
known  as  antitoxin.  This  occurs  abundantly  in  its 
blood,  a  gallon  or  more  of  which  is  later  drawn  from 
a  vein  in  its  neck.  After  the  corpuscles  are  allowed  to 
settle,  the  clear  part,  called  serum,  containing  the  anti- 


HOSPITALS   AND   SANATORIA  289 

toxin,  is  put  up  in  tubes  and  sent  out  to  physicians  to 
prevent  and  cure  diphtheria. 

Antitoxin  does  not  affect  the  heart,  as  many  people  sup- 
pose, but  the  poison  of  the  diphtheria  germs  does.  Anti- 
toxin used  in  the  early  stages  of  the  disease  is  a  sure  cure 
in  nearly  all  cases.  It  saves  the  lives  of  45,000  children 
in  Germany  every  year.  The  mortality  from  diphtheria 
is  only  one  third  as  great  as  in  former  years.  Antitoxin 
saves  the  lives  of  more  than  10,000  persons  annually  in 
the  United  States.  In  the  Boston  City  Hospital  before 
the  use  of.  antitoxin  46  per  cent  of  the  diphtheria  patients 
died,  but  with  the  use  of  antitoxin  since  1895  only  12 
per  cent  die. 

Hospitals  and  Sanatoria.  —  In  nearly  every  city  in  the 
United  States  with  a  population  of  over  20,000  there 
are  one  or  more  hospitals.  These  are  institutions  with 
nurses,  surgeons,  and  physicians  and  all  appliances  for  the 
treatment  of  the  sick  and  wounded.  Serious  operations 
are  usually  performed  with  more  safety  and  less  expense 
at  the  hospital  than  at  the  home.  The  thousands  who  are 
living  in  hotels  and  private  boarding  houses  find  the 
hospital  a  convenient  place  to  receive  them  in  case  of 
sickness.  A  specially  equipped  wagon,  called  an  am- 
bulance,  is  kept  by  most  hospitals  for  conveying  the  sick 
and  injured  to  the  institution. 

Although  many  persons  using  the  hospitals  pay  for 
their  accommodations,  yet  there  are  hundreds  who  cannot 
afford  the  expense,  and  are  therefore  treated  free.  A 
department  of  the  public  hospitals,  known  as  the  dis- 
pensary, furnishes  free  of  charge  treatment  and  medicines 
to  the  poor  making  application  at  certain  hours  each  day. 

OAV.   PHT8.  19 


290  THE  PREVENTION   OF   DISEASE 

Public  hospitals  are  largely  maintained  by  the  generous 
gifts  of  benevolent  persons  or  by  the  government.  A 
hospital  for  taking  care  of  those  not  in  their  right  mind 
is  an  insane  asylum.  Each  state  usually  supports  one  or 
two  such  institutions.  A  sanatorium  is  a  hospital  where 
the  sick  are  treated  largely  by  the  use  of  fresh  air,  nutri- 
tious food,  proper  exercise,  and  baths. 

It  is  not  only  humane  to  prevent  suffering,  but  it  is 
economy  for  the  government  to  endeavor  to  prevent  sick- 
ness and  cure  the  sick,  because  the  average  work  of  each 
person  done  between  the  ages  of  21  and  75  years  is  worth 
to  the  country  about  $4000.  The  captivity  of  the  Jews 
was  delayed  122  years  by  the  plague  that  fell  upon  the 
army  of  Sennacherib.  Herodotus,  the  great  Greek  his- 
torian, tells  us  that  nothing  reduced  the  Athenian  power 
more  than  the  plague  or  contributed  more  largely  to  the 
downfall  of  Athens.  One  of  the  greatest  assets  of  any 
nation  is  healthy  citizens. 

The  Board  of  Health.  —  In  nearly  every  community 
there  are  several  persons  appointed  to  protect  the  health 
of  the  people.  These  persons  constitute  the  Board  of 
Health.  One  of  their  number,  the  health  officer,  is  re- 
quired to  see  that  certain  laws  are  enforced  to  prevent  the 
cause  of  sickness  and  the  spread  of  contagious  diseases. 
One  of  his  duties  is  to  placard  all  houses  in  which  are 
contagious  diseases,  to  quarantine  the  inmates,  and  to 
disinfect  the  home  after  the  sick  have  recovered. 

It  is  the  duty  of  the  health  board  to  see  that  the  gar- 
bage is  burned  or  buried  and  the  sewage  properly  disposed 
of,  to  prevent  the  sale  of  unhealthful  milk  and  provide  for 
a  pure  supply  of  water. 


HEALTH   RULES    FOR   SCHOOL   CHILDREN  291 

All  persons  should  obey  the  instructions  of  the  board  of 
health  and  endeavor  to  assist  them  in  preventing  much 
sickness  which  frequently  afflicts  every  negligent  com- 
munity. 


HEALTH   RULES  FOR  SCHOOL   CHILDREN 

FROM  THE  MICHIGAN  PUBLIC  HEALTH  QUARTERLY 

1.  Health  is  wealth. 

2.  Do  not  put  pins  in  your  mouth. 

3.  Do  not  hold  money  in  your  mouth. 

4.  Do  not  put  your  fingers  in  your  mouth. 

5.  Do  not  put  pencils  in  your  mouth  or  wet  them  with 

your  lips. 

6.  Do  not  wet  your  finger  in  your  mouth  when  turning 

the  leaves  of  books. 

7.  Do  not  put  anything  into  your  mouth  except  food 

and  drink. 

8.  Never  spit  on  your  slate,  or  upon  the  floor  or  side- 

walk. 

9.  Do  not  pick  your  nose,  or  wipe  it  with  your  hand 

or  sleeve. 

10.  Keep  your  face,  hands,  and  finger  nails  clean. 

11.  Keep  the   interior  of  your   body  clean  by  allowing 

nothing  to  go  into  it  excepting  pure  food  and  pure 
drink. 

12.  Don't  keep  your  rubbers  on  in  the  schoolroom. 

13.  Don't  sit  with  wet  feet  or  damp  clothing  ;   resort  to 

the  stove  or  register  until  they  are  dry. 

14.  Do  not  swap  parts  of  apples,  candy,  chewing  gum, 


292  THE   PREVENTION    OF   DISEASE 

half-eaten  food,  whistles,  or  anything  that  is  to  be 
put  in  the  mouth. 

15.  Never   cough  or   sneeze   in  a  person's   face.     Turn 

your  face  to  one  side,  and  hold  a  handkerchief 
before  your  mouth. 

16.  When  drinking  rinse  out  the  cup,  and  empty  what 

water  you  leave  into  the  wash  basin  or  sink. 

17.  Breathe  only  fresh  air  day  and  night  —  simply  avoid 

drafts. 

18.  Breathe,  sit,  stand,  and  walk  correctly.     In  so  doing 

you  will  do  more  to  prevent  consumption  than  all 
the  physicians  combined.  A  good  pair  of  lungs 
is  the  most  efficacious  barrier  to  this  disease. 

19.  Go  to  bed   early,    rise  early;    and  take   plenty   of 

"physical  culture,"  helping  father  and  mother 
before  and  after  school  with  the  "  chores." 

20.  Study  the  physiology  —  to  know  how  to  use  rightly 

and  take  proper  care  of  every  part  of  the  body. 

Questions 

1.  Name  three  methods  of  preventing  disease.  2.  Why  should  the 
germs  in  the  excretions  of  the  sick  always  be  killed  ?  3.  How  should 
the  excretions  be  treated  ?  4.  Who  are  largely  responsible  for  the 
many  deaths  from  typhoid  fever?  5.  Why  should  open  spittoons  not 
be  used  ?  6.  How  should  the  spit  of  the  sick  be  disposed  of  ?  7.  Why 
and  how  should  those  sick  with  contagious  diseases  be  isolated? 
8.  J^ame  some  antiseptics.  9.  What  is  an  antiseptic  ?  10.  Why 
should  a  room  containing  a  person  sick  with  a  contagious  disease  not 
be  swept?  11.  How  should  a  room  be  disinfected  ?  12.  Explain  how 
the  person  should  be  disinfected.  13.  When  one  case  of  typhoid 
occurs  in  a  family,  why  do  other  members  of  the  house  often  get  the 
disease?  14.  What  five  kinds  of  disease  germs  may  usually  be  kept 
out  of  the  body?  15.  How  may  these  germs  be  kept  out  of  the  body? 
16.  When  should  one  use  only  boiled  water  ?  17.  How  may  the  germs 


SUGGESTIONS    FOR    THE   TEACHER  293 

of  malaria  and  yellow  fever  be  kept  out  of  the  system  ?  18.  Give  two 
differences  between  the  malaria  mosquito  and  the  common  mosquito. 
19.  How  may  the  plague  and  leprosy  be  transmitted  ?  20.  In  \vhat 
way  are  the  germs  given  off  by  those  sick  with  diphtheria  and  tuber- 
culosis ?  21.  Why  should  every  one  hold  a  handkerchief  over  the 
mouth  when  coughing?  22.  Ho\v  is  water  filtered  and  what  is  the 
result?  23.  What  facts  show  that  filtering. river  water  saves  much 
sickness  and  death  ?  24.  How  are  disease  germs  often  killed  within 
the  body  ?  25.  How  may  the  body  be  rendered  safe  against  some 
diseases?  26.  How  frequently  are  the  germs  of  tuberculosis  present 
in  the  body  ?  27.  Give  the  number  of  people  dying  annually  from 
tuberculosis.  28.  Explain  the  method  of  preventing  tuberculosis. 
29.  Give  evidence  showing  that  hygienic  living  will  in  most  cases  pre- 
vent tuberculosis.  30.  Why  is  it  better  for  tubercular  patients  to  sleep 
out  of  doors  ?  31.  How  may  a  person  often  distinguish  consumption 
from  a  cold  or  catarrh?  32.  Are  patent  medicine  or  alcoholic  drinks 
of  any  use  in  curing  consumption?  33.  Give  three  great  helps  in  cur- 
ing consumption.  34.  Give  evidence  showing  that  in  most  cases  con- 
sumption may  be  cured  in  the  early  stages.  35.  Can  one  live  in  the 
same  house  with  a  consumptive  without  danger?  36.  What  is  vacci- 
nation? 37.  How  is  smallpox  prevented?  38.  State  some  facts 
showing  that  smallpox  was  once  a  much-dreaded  disease.  39.  What 
facts  show  that  vaccination  for  smallpox  prevents  the  disease? 
40.  What  care  should  be  used  in  vaccinating?  41.  Where  is  anti- 
toxin for  diphtheria  secured  ?  42.  Of  what  use  is  a  hospital,  a  dispen- 
sary, or  a  sanatorium  ? 

Suggestions  for  the  Teacher 

1.  Write  to  the  Department  of  Agriculture,  Washington,  D.C.,  for 
bulletins  relating  to  tuberculosis  and  health.     They  furnish  excellent 
material  for  short  essays  by  the  pupils. 

2.  Ask  the  pupils  to  find  the  young  of  mosquitoes  by  looking  into 
any  quiet  ponds,  tin  cans,  or  barrels  containing  water.     The  young 
will  hatch  into  full-grown  mosquitoes  in  a  few  days  if  kept  in  a  jar  of 
water.     Let  the  pupils  suggest  plans  for  destroying  mosquitoes. 

3.  Ask  the  pupils  to  note  how  many  persons  spit  upon  the  sidewalk 
and  floor  of  cars  and  public  buildings.     Ask  fhe  class  to  think  the 
matter  over  and  suggest  a  remedy  for  the  uncleanly  habit.     Ask  some 
of  the  boys  to  count  the  flies  seen  feeding  in  spittoons. 


XXV.     ACCIDENTS   AND   EMERGENCIES 

Importance  of  Early  Aid.  —  It  is  estimated  that  over 
10,000  people  die  annually  in  this  country  from  lack  of 
the  quick  aid  after  injury  which  this  chapter  explains. 
During  the  late  hours  of  night  it  is  not  easy  to  secure  a 
physician  in  less  than  an  hour,  and  in  the  country  many 
residents  have  no  doctor  within  five  or  more  miles  of 
them.  The  most  effective  aid  in  cases  of  fainting,  con- 
vulsions, sunstroke,  snake  bite,  croup,  choking,  bleeding, 
and  drowning  is  that  given  during  the  first  half  hour 
after  the  person  is  affected. 

Injuries  to  the  eye  and  ear  are  discussed  in  the  chapters 
treating  of  those  organs.  Treatment  for  sprains  and  dis- 
locations is  given  in  the  chapter  on  bones. 

Fainting.  —  Fainting  may  be  caused  by  pain,  fatigue, 
loss  of  blood,  the  sight  of  some  gruesome  object,  such  as 
flowing  blood,  or  by  a  hot  and  badly  ventilated  room. 
The  face  is  pale,  the  lips  white,  and  the  breathing  is 
quickened,  while  cold  sweat  appears  on  the  brow  and  the 
palms  of  the  hands.  As  fainting  is  caused  by  an  insuf- 
ficient supply  of  blood  to  the  brain,  the  patient  should  be 
laid  flat  on  the  floor.  Then  the  doors  and  windows  must 
be  opened  and  the  clothing  loosened,  while  cold  water  is 
sprinkled  on  the  face.  Recovery  should  occur  in  a  few 
minutes.  As  soon  as  the  patient  is  able  to  swallow 

294 


FITS   OR   CONVULSIONS  295 

give  sips  of  hot  milk  or  water.  Swallowing  stimulates  the 
heart.  Do  not  give  alcohol. 

Intoxication.  —  This  may  be  caused  by  the  drinking  of 
beer,  wine,  whisky,  hard  cider,  or  patent  medicines  con- 
taining alcohol.  The  victim  seems  half  asleep,  eyes 
are  red  and  bloodshot  and  have  a  fixed  stare.  The 
breathing  is  slow,  and  the  smell  of  liquor  is  often  in  the 
breath.  The  stomach  should  be  emptied  by  giving  the 
patient  a  tablespoonful  of  mustard  in  warm  water  to 
make  him  vomit.  Then  let  him  sip  slowly  two  or  three 
cups  of  strong  hot  coffee,  after  which  he  may  be  put  to  bed. 

Fits  or  Convulsions.  —  There  are  in  this  country  about 
135,000  people  who  are  attacked  at  intervals  of  several 
hours  or  days  \\iihepilepticfits.  The  victim  is  unable  to 
control  his  muscles  and  throws  his  arms  and  legs  in  all 
directions.  He  seems  to  be  in  agony,  but  really  does  not 
suffer.  No  remedy  is  effective. .  The  patient  should  be 
prevented  from  injuring  himself,  and  especially  from  bit- 
ing his  tongue,  by  placing  a  folded  handkerchief  between 
the  teeth.  The  fit  will  last  only  a  few  minutes. 

Convulsions  or  spasms  are  usually  ailments  of  children 
less  than  five  years  of  age.  They  are  frequently  caused 
by  eating  indigestible  foods,  such  as  fruits  and  nuts,  which 
are  not  well  chewed.  The  child  jerks  at  first  with  con- 
tractions of  the  muscles  and  then  struggles  violently.  It 
is  unconscious,  and  therefore  does  not  suffer.  Relief  is 
usually  given  by  placing  the  feet  and  legs  in  water  as  hot 
as  the  hand  can  bear  and  applying  a  cloth  wrung  out  of 
cold  water  to  the  forehead  and  temples.  The  wet  cloth 
should  be  changed  every  minute  or  two  to  keep  the  head 
as  cold  as  possible.  The  bowels  should  be  moved. 


296 


ACCIDENTS   AND   EMERGENCIES 


Sunstroke  and  Heat  Exhaustion.  —  Sunstroke  is  caused 
by  fatigue  and  exposure  to  the  rays  of  the  sun  on  a  hot 
day.  The  patient  feels  giddy  at  first,  then  weak  and 
sick  at  the  stomach.  He  may  become  sleepy  and  more 
or  less  unconscious.  The  eyes  are  bloodshot  and  the 
skin  is  hot  and  dry.  The  remedy  is  to  keep  the  patient 


FIG.  195.  —  Method  of  producing  artificial  breathing. 

cool  by  throwing  cold  water  on  the  head,  neck,  and  chest 
or  by  ^  wrapping  sheets  wrung  out  of  cold  water  around 
him.  Chopped  ice  wrapped  in  flannel  may  be  applied  to 
the  head. 

In  heat  exhaustion  the  skin  is  cold  and  pale,  and 
therefore  cool  applications  should  not  be  used.  Drinking 
strong  hot  coffee  and  rest  in  bed  are  most  helpful. 


THE   CLOTHING    ON   FIRE  297 

Alcoholic  drink  should  never  be  given  for  sunstroke  or 
heat  exhaustion. 

Suffocation  from  Gas  or  Drowning.  —  Suffocation  may  be 
produced  by  remaining  in  a  closed  room  where  the  gas 
used  in  lighting  is  escaping,  or  by  the  gas  from  a  coal 
stove  when  the  chimney  draft  is  closed.  The  first  remedy 
is  fresh  air  in  abundance.  All  tight  clothing  must  be 
loosened  and  artificial  respiration  begun  at  once  by  lay- 
ing the  patient  face  downward  with  his  chest  on  a  thick 
folded  coat  or  blanket.  Then  stand  astride  him,  and  plac- 
ing one  hand  on  either  side  of  the  lower  ribs,  let  the 
weight  of  your  body  fall  forward  slowly,  and  thus  press 
out  the  air  in  the  lungs  and  mucus  in  the  larynx.  The 
hands  should  not  be  moved  from  their  places,  but  the 
pressure  should  be  slowly  relaxed  by  bringing  your  body 
to  a  more  upright  position  so  that  the  air  will  be  drawn 
into  the  lungs.  The  operator  should  bend  forward  and 
backward,  pressing  on  the  ribs  and  relaxing  the  pressure 
about  fifteen  times  a  minute,  while  another  person  is 
dashing  cold  water  upon  the  head  and  rubbing  the  body 
to  warm  it. 

In  case  of  apparent  drowning  the  artificial  breathing 
should  be  begun  at  once  without  making  any  effort  to  get 
the  water  out  of  the  internal  organs.  The  wet  clothing 
should  be  removed  as  soon  as  possible,  and  dry  blankets 
used  with  hot  bricks  to  warm  the  body.  Strong  hot 
coffee  is  useful  as  a  stimulant  as  soon  the  patient  can 
swallow. 

The  Clothing  on  Fire.  —  To  extinguish  the  burning 
clothing  of  a  person,  it  is  necessary  to  wrap  him  in  a  coat, 
quilt,  or  blanket  so  as  to  exclude  the  air.  Rolling  him 


298  ACCIDENTS    AND   EMERGENCIES 

over  and  over  in  the  dirt  and  dust  is  also  effective.  As 
the  patient  is  in  pain  and  much  excited,  he  is  likely  to 
break  loose  and  run  out  into  the  open  air  unless  held 
firmly.  If  the  burning  is  sufficient  to  cause  the  clothes 
to  adhere  to  the  skin  in  places,  these  should  be  soaked  in 
a  quart  of  water  to  which  a  teacupful  of  washing  or  bak- 
ing soda  has  been  added,  while  the  physician  is  sent  for. 
The  slightly  burned  places  may  be  anointed  with  vaseline. 

Burns  and  Scalds.  —  Hot  water  or  escaping  steam  may 
cause  severe  scalds.  Burns  are  produced  by  fire,  hot  ob- 
jects, acids,  and  alkalies.  Every  household  should  keep  on 
hand  a  quart  bottle  filled  with  one  pint  of  limewater  and 
one  pint  of  linseed  oil  well  shaken.  This  is  carron  oil,  the 
most  effective  of  all  remedies  for  burns  and  scalds.  Linen 
cloths  or  pieces  of  lint  are  soaked  in  this  and  applied  at 
once  to  the  burn.  Cloths  spread  with  vaseline  or  soaked 
in  kerosene  or  in  a  pint  of  water  containing  a  half  tea- 
cupful  of  soda  and  bound  on  the  injured  skin  give  great 
relief. 

Burns  from  acids  should  be  first  drenched  with  water 
containing  a  little  soda  before  the  above  remedies  are 
applied.  Burns  from  alkalies  should  be  washed  with 
water  containing  a  little  vinegar  before  using  the  other 
remedies. 

Frostbite.  —  Frosted  ears,  fingers,  and  toes  are  very 
common,  and  often  cause  much  discomfort  for  several 
weeks  if  not  properly  cared  for.  The  parts  affected 
should  be  rubbed  with  snow  or  ice  water  in  a  cold  room 
until  a  tingling  sensation  is  felt.  This  shows  that  the 
circulation  which  had  stopped  has  returned,  and  the 
patient  may  then  be  brought  nearer  a  warm  stove. 


BRUISES 


299 


Cuts  and  Nail  Punctures.  —  A  small  cut  or  the  puncture 
of  the  skin  by  a  nail  has  been  known  to  result  in  death. 
This  was  due  to  bacteria,  which  cause  the  pus  or  white 
matter  in  a  sore.  If  a  wound  bleeds  freely,  the  germs  are 
likely  to  be  washed  out.  In  case  the  skin  is  torn  or 
punctured  by  a  blunt  instrument  like  a  nail  the  wound 
should  be  well  washed 
out  by  forcing  into  it 
with  a  syringe  tur- 
pentine or  a  five  per 
cent  solution  of  car- 
bolic acid.  A  clean 
linen  cloth  folded  sev- 
eral times  should  then 
be  laid  over  the  wound 
and  tied  firmly  in  place. 
If  the  wound  causes 
a  considerable  flow  of 
blood,  it  should  be  Fl°- 196'  —  Bacteria  whi<*  get  into  wounds 

and  produce  blood  poison. 

stopped,     as     directed 

in  the  chapter   on   the  circulatory  system.     Do  not  use 

unboiled  water  or  a  soiled  cloth  or  hands  in  cleaning  a 

wound. 

Bruises.  —  These  result  from  blows  on  the  person  with 
blunt  instruments.  The  part  affected  swells  and  becomes 
more  or  less  black  and  blue,  owing  to  the  bursting  of  the 
blood  vessels.  The  dark  coloration  may  be  prevented  to 
a  certain  extent  by  applying  for  a  half  hour  cloths  wrung 
out  of  very  hot  water.  The  cloths  should  be  changed 
every  two  or  three  minutes.  Cold  water  will  serve 
almost  as  well  as  hot  water. 


300 


ACCIDENTS    AND    EMERGENCIES 


Bleeding  from  the  Nose.  —  This  is  rarely  dangerous,  and 
no  remedy  is  necessary  unless  the  blood  continues  to  flow 
for  an  hour  or  more.  The  patient  should  not  lean  over, 
but  sit  erect  or  with  the  head  thrown  slightly  backward 
and  use  a  damp  cloth  to  soak  up  the  blood.  Broken  ice 
tied  in  a  cloth  and  applied  to  the  back  of  the  neck  and 
between  the  shoulder  blades  is  the  best  remedy.  Cloths 


FIG.  197.  —  How  a  copperhead  snake  or  pilot  sinks  its  poison  fangs  or  teeth 
into  the  flesh. 


wrung  out  of  cold  water  may  be  held  to  the  back  of  the 
neck  and  over  the  nose  and  forehead.  If  bleeding  con- 
tinues, the  nose  should  be  held  shut  and  the  mouth  used 
in  breathing. 

Bites  and  Stings  of  Animals.  — The  bite  of  a  healthy  dog 
or  cat  should  be  treated  like  any  other  wound.  If  there 
is  any  reason  to  suppose  the  dog  is  rabid,  a  physician 
should  be  called  to  cauterize  the  bite  and  arrange  to 
vaccinate  the  patient  for  hydrophobia. 

The  bite  of  a  venomous  or  harmful  snake,  such  as  a  copper- 
head, rattlesnake,  or  moccasin,  usually  results  in  death  in 


CHOKING  301 

from  12  to  24  hours  unless  some  remedy  is  used.  A  physi- 
cian should  be  called  at  once.  The  best  means  of  avoiding 
serious  results  if  the  bite  is  on  a  limb  is  to  tie  just  above 
the  punctures  a  loose  bandage  and  twist  it  tight  by  turn- 
ing a  stick  slipped  underneath.  Then  a  cut  lengthwise 
of  the  limb  two  inches  long  and  nearly  a  half  inch  deep 
should  be  made  through  the  wound  to  let  out  the  poi 
soned  blood  and  lymph.  The  application  to  the  bite  of 
crystals  of  permanganate  of  potash  is  of  great  value.  If  the 
physician  does  not  arrive  soon,  the  taking  of  a  tablespoon- 
ful  of  whisky  at  intervals  of  a  half  hour  until  the  patient 
feels  the  effect  tends  to  keep  up  the  action  of  the  heart. 

Some  of  the  snakes,  such  as  the  water  snake,  without  any 
poison,  bite  sufficiently  to  make  the  blood  run,  but  no 
serious  results  follow.  The  bite  of  a  poisonous  snake  can 
be  recognized  by  the  presence  of  two  little  holes  made  by 
the  two  fangs  in  the  upper  jaw  of  the  reptile.  The  bite 
of  a  spider  need  cause  no  alarm  unless  it  is  one  of  the 
large  Southern  spiders. 

The  stings  of  wasps  and  bees  are  not  dangerous,  but  may 
cause  considerable  swelling  and  pain.  This  may  be  re- 
lieved by  bathing  the  part  in  ammonia  or  a  strong  solution 
of  baking  .soda  in  water. 

Choking.  —  The  lodging  of  a  button,  thimble,  or  a  piece 
of  meat  in  the  throat  may  cause  death  in  a  few  minutes. 
A  blow  with  the  fist  on  the  back  between  the  shoulder 
blades  will  cause  the  air  to  rush  out  of  the  lungs  and 
sometimes  expel  the  object.  If  the  sufferer  is  a  child,  it 
should  be  held  by  the  feet  with  the  head  hanging  down- 
ward while  two  or  three  blows  are  struck  on  the  back  of 
the  chest. 


302 


ACCIDENTS    AND   EMERGENCIES 


Sometimes  the  object  is  in  the  upper  part  of  the  throat 
and  may  be  pulled  out  with  the  finger  or  the  end  of  a 
bent  spoon  handle.  When  hard  objects,  like  keys  or 
tacks,  are  swallowed,  plenty  of  hard-boiled  eggs,  bread, 

and  potatoes  should 
be  eaten.  These  will 
prevent  the  jagged 
points  of  the  object 
from  injuring  the  in- 
testine. 

Croup.  —  There  are 
two  kinds  of  croup. 
False  or  catarrhal  croup 
usually  comes  on  sud- 
denly at  night.  The 
child  has  a  hoarse 
metallic  cough  and 
may  at  times  have  to 
gasp  for  breath.  Re- 
lief may  be  quickly 


Fia.  198.  —  The  death  cup,  a  poisonous  mush- 
room which  has  killed  more  people  than 
any  other.  The  different  forms  show  the 
plant  at  different  ages. 


given  by  making  a 
tent  of  a  sheet  or 
quilt  in  which  the 
child  should  be  held, 

while  a  tin  cup  partly  filled  with  a  mixture  of  equal  parts 
of  vinegar  and  water  is  kept  boiling  or  very  hot  on  an 
oil  stove  in  the  tent.  A  common  lamp  may  be  used  to  do 
the  heating  if  two  nails  for  the  support  of  the  cup  are 
laid  across  the  top  of  the  chimney  to  prevent  smoking. 

Membranous  croup  is  a  form  of  diphtheria  in  which  there 
is  a  membrane  formed  in  the  narrow  part  of  the  throat. 


SPECIAL  POISONS 


303 


Poisons  and  Emetics.  —  An  emetic  is  a  substance  which, 
when  taken  into  the  stomach,  causes  vomiting.  Since  the 
first  step  in  treating  a  person  poisoned  is  usually  to  free  the 
stomach  of  its  contents,  an  emetic  must  be  given.  It  is 
well  to  remember  that  no 
emetic  should  be  used  when 
from  stains  or  burns  on  the 
fingers,  lips,  or  mouth,  or 
by  any  other  means  it  is 
known  that  the  person  has 
taken  a  strong  alkali  or 
an  acid. 

The  following  are  good 
emetics:  a  tablespoonful  of 
mustard  in  a  glass  of  warm 
water ;  two  tablespoonfuls 
of  common  salt  in  a  glass 
of  warm  water;  a  pint  of 
warm  water  followed  by 
tickling  the  back  of  the 
throat  with  a  feather  or 
other  soft  object.  Poisons 
cause  the  death  of  about 
8000  persons  annually. 

Special  Poisons.  —  The  remedy  for  carbolic  acid  poisoning 
is  a  tablepoonf  ul  of  "  salts,"  properly  called  Epsom  salts,  or 
sulphate  of  magnesia,  in  a  glass  of  warm  water.  Im- 
mediately after  a  pint  or  two  of  milk  should  be  swallowed. 
A  cup  of  strong  coffee  may  then  be  given  to  stimulate  the 
heart.  Ammonia  or  potash  poisoning  may  be  helped  by 
giving  the  patient  the  juice  of  two  or  three  lemons  or 


FIG.  199.  —  Water  hemlock,  whose 
poisonous  roots  have  killed  a  num- 
ber of  children.  The  height  of  the 
plant  is  from  three  to  five  feet  and 
the  leaves  are  two  or  three  inches 
long. 


304 


ACCIDENTS   AND    EMERGENCIES 


oranges,  or  a  glass  of  water  containing  two  tablespoonfuls 
of  vinegar. 

Arsenic  poisoning  is  common,  as  this  poison  forms  a  part 
of  Paris  green,  many  rat  poisons,  and  preserving  fluids. 

After  giving  an  emetic,  a  glass 
or  two  of  soapy  or  greasy  water 
should  be  taken.  A  cup  of 
water  which  has  been  several 
days  in  a  rusty  kettle  or  con- 
tained rusty  nails  or  iron  of 
any  kind  should  be  drunk. 

Certain  plants  found  grow- 
ing in  yards  and  fields  contain 
strong  poisons.  The  deadly 
nightshade,  some  kinds  of 
mushrooms,  holly  berries,  jimson 
weed,  and  water  hemlock  have 
caused  the  deaths  of  many 
persons,  especially  children. 
The  roots,  berries,  or  leaves  of 
wild  plants  should  never  be 
chewed  or  eaten  unless  they 
are  known  to  be  harmless,  as 
there  are  more  than  thirty 

poisonous  plants  growing  in  the  United  States.  The 
best  remedy  for  their  poisons  is  an  emetic,  followed  by 
a  large  dose  of  Epsom  salts  to  cause  the  harmful  materials 
to  pass  out  of  the  alimentary  canal.  A  physician  should 
be  called  at  once. 

The  external  poisoning  of  the  skin  by  poison  ivy  or  sumac 
often   results  seriously.     Numerous   pimples   or   blisters 


FIG.  200.  —  Poison  ivy,  which  is 
common  along  old  fences  and 
in  waste  places.  Touching  it 
or  sometimes  even  coming 
near  it  poisons  the  skin  of 
many  persons. 


SUGGESTIONS    Foil    THE   TEACHER  305 

may  form  with  more  or  less  redness  and  swelling,  some- 
times sufficient  to  close  the  eyes.  Poison  ivy  may  be 
distinguished  from  similar  vines  by  the  division  of  each 
leaf  into  three  leaflets  instead  of  five.  If  one  has  been 
touching  the  plant,  poisoning  may  usually  be  prevented 
by  washing  as  soon  as  possible  the  face  and  hands  with- 
soapsuds.  A  good  remedy  for  the  poison  is  the  applica- 
tion to  the  affected  parts  of  a  cloth  soaked  in  a  half 
pint  of  equal  parts  of  alcohol  and  water  containing  as^ 
much  sugar  of  lead  as  will  dissolve. 

Questions 

1.  Why  should  every  one  understand  how  to  give  first  aid  to  the 
injured  ?  2.  What  may  cause  fainting  ?  3.  How  should  a  fainting 
person  be  treated  ?  4.  What  is  the  remedy  for  intoxication?  5.  What 
is  the  treatment  for  epileptic  fits?  6.  How  can  you  tell  when  a- 
child  is  having  a  spasm?  7.  Explain  the  treatment  for  a  spasm^ 

8.  Describe  the  difference  between  sunstroke  and  heat  exhaustion* 

9.  How  is  a  patient  to  be  treated  in  case  of  suffocation  ?     10.  Explain 
the  relief  for  scalds  and  burns.     11.  What  is  the  remedy  for  frost- 
bite?     12.    Describe   the   treatment    for   cuts   and  nail  punctures. 
13.  How  should  a  bruise  be  treated?     14.  Give  some  methods  for 
stopping  the  flow  of  blood  from  the  nose.     15.  Why  is  the  bite  of  a 
black  snake,  garter  snake,  or  common  water  snake  harmless  ?     16.  How 
is  the  bite  of  a  copperhead  or  rattlesnake  to  be  treated  ?     17.  Describe 
the  relief  for  choking.     18.  How  does  false  croup  differ  from  mem- 
branous croup  ?     19.  What  relieves  false   croup  ?     20.  Name  some 
emetics.    21.  Of  what  use  are  emetics  ?    22.  When  should  an  emetic 
not  be  given  ?    23.  What  is  the  remedy  for  carbolic  acid  poisoning  ? 
24.  Name  some  poisonous  plants.    25.  Explain  how  poisoning  of  the 
skin  by  poison  ivy  may  be  relieved. 

Suggestions  for  the  Teacher 

Any  one  able  to  render  efficient  first  aid  to  the  injured  is  a  valuable 
person  in  any  community.  It  is  worth  while  for  the  teacher  to  take 
time  to  impress  upon  the  children  what  to  do  when  the  various 

DAT.   PHYS.  — 20 


306  ACCIDENTS    AND   EMERGENCIES 

common  accidents  of  life  occur.  This  may  be  done  by  full  and  clear 
explanations  followed  by  careful  questioning  of  the  pupils.  Actual 
demonstrations  of  how  to  proceed  in  case  of  certain  accidents,  such  as 
fainting,  choking,  bums,  and  wounds,  may  be  given,  using  some  pupil 
for  the  subject. 

Permitting  the  children  to  tell  of  accidents  that  have  occurred  in 
their  own  families  and  the  results  of  the  wrong  or  right  treatment 
given,  may  often  help  to  emphasize  the  importance  of  understanding 
what  this  chapter  teaches.  Procure  from  the  Department  of  Agricul- 
ture at  Washington  the  free  pamphlets  on  poisonous  plants  and 
mushrooms. 


PRONUNCIATION  AND    EXPLANATION   OF 
DIFFICULT   WORDS 

Ab  do'men  :  that  part  of  the  body  between  the  chest  and  legs. 

Ab  dom'i  nal:  pertaining  to  the  abdomen. 

Ad'e  noids :  spongy  growths  in  the  upper  part  of  the  throat  back  of 
the  nose. 

A  dul  ter  a'tion :  making  any  substance  impure  by  mixing  with  it 
something  of  less  value. 

Al  bu'min :  one  kind  of  proteid.     It  occurs  in  all  cells  of  the  body. 

Al'co  hoi  ism  :  a  diseased  condition  of  the  body  caused  by  using  much 
strong  drink. 

Am'bu  lance  :  a  wagon  for  carrying  the  sick. 

A  moe'ba :  a  tiny  one-celled  animal  which  is  constantly  changing  its 
shape. 

A  mce'boid :  like  an  amoeba. 

A  nat'o  my  :  the  study  treating  of  the  parts  of  the  body. 

An  ti  sep'tic  :  that  which  stops  the  growth  of  bacteria. 

An  ti  tox'in :  a  substance  which  prevents  certain  poisons  from  harm- 
ing the  body.  And  means  against,  and  toxin,  a  poison.  Anti- 
toxin for  diphtheria  makes  the  poison  given  off  by  the  diphtheria 
germs  harmless. 

Ap'oplexy:  sudden  loss  of  motion  and  fainting  caused  by  the  clog- 
ging or  bursting  of  a  blood  vessel  in  the  brain. 

Append  ici'tis:  an  inflammation  of  the  vermiform  appendix. 

A'que  ous  (a'kwe  us)  :  the  kind  of  humor  or  watery  fluid  in  the  front 
part  of  the  eyeball. 

A  rach'noid  (a  rak'noid)  :  a  delicate  membrane  covering  the  brain 
and  spinal  cord. 

Asth'ma  (as'ma)  :  a  disease  in  which  the  air  tubes  are  squeezed  so 
tight  by  their  muscles  as  to  hinder  proper  breathing. 

Astigmatism:  a  condition  of  unequal  curvature  in  the  lens  or 
cornea. 

307 


308      PRONUNCIATION    AND   EXPLANATION    OF    WORDS 

Au'di  to  ry :  relating  to  the  ear. 

Ax'on :  the  long  process  of  a  nerve  cell  carrying  the  stimulus  from  the 
cell  body. 

Ba  cil'li :  rodlike  bacteria  such  as  the  germs  of  diphtheria  and  con- 
sumption. 

Ba  cirrus  :  singular  of  bacilli. 

Bac  te'ri  a :  tiny  one-celled  plants  often  called  germs  or  microbes. 

Bi  cus'pid :  another  name  for  a  prernolar  tooth,  also  the  valve  on  the 
left  side  of  the  heart. 

Bracb/i  al  (brakfiat)  :  pertaining  to  the  arm. 

Bron'chi  (brnn'ki)  :  plural  of  bronchus. 

Bron'chial  tubes  (Jron'kial)  :  the  air  tubes  of  the  lungs. 

Bron  chi'tis  (bron  ki'tis)  :  inflammation  of  the  bronchial  tubes. 

Bron'chus  (bron'kus)  :  one  of  the  two  branches  of  the  windpipe  enter- 
ing  the  lungs. 

Caf  fe'in :  a  bitter  substance  in  coffee  and  tea. 

Cal'o  rie  :  a  heat  unit. 

Ca  nine'  teeth  :  the  stomach  or  eye  teeth. 

Cap'il  la  ry :  the  smallest  blood  tube. 

Car  bo  hy'drate :  any  food  stuff  made  mostly  of  starch  or  sugar. 

Car  bol'lc  ac'id  :  a  poison  which  burns  the  skin.  It  is  used  as  a  disin- 
fectant. 

Car'di  ac  :  near  to  or  belonging  to  the  heart. 

Ca'se  in:  the  proteid  in  milk  and  cheese. 

Ce  ment' :  the  substance  covering  the  dentine  in  the  roots  of  the  teeth. 

Cer  e  bel'lum  :  the  little  brain ;  the  large  lobe  of  the  hind  brain. 

Cer'e  brum :  the  large  part  of  the  brain. 

Chol'e  ra  infan'tum:  a  dangerous  disease  of  children  usually  caused 
by  impure  milk,  or  dirty  milk  bottles. 

Cho'roid  (ko'roid)  :  the  middle  coat  of  the  eyeball. 

Chyle  (kite)  :  the  digested  food  in  the  intestine. 

Chyme  (Jdme)  :  the  partly  digested  food  leaving  the  stomach. 

Cil'ia:  tiny  hairlike  projections  in  the  nose  and  air  tubes.  They 
catch  dust  particles  and  mucus,  and  move  them  outward  by  con- 
stantly waving. 

Clav'i  cle  :  collar  bone. 

Co'ca  ine  (ko'ka  in)  :  a  narcotic  made  from  coca  leaves. 

Coc'ci  (kok'si)  :  spherical  bacteria. 


PRONUNCIATION    AND    EXPLANATION    OF   WORDS      309 


(kok'siks)  :  the  small  bone  at  the  end  of  the  spinal  column. 
Coch'le  a  (kok'le  a)  :  coiled  part  of  the  internal  ear. 
Com'mis  sure  :  a  band  of  fibers  in  the  brain  or  spinal  cord. 
Con  sti  pa'tion  :  a  condition  in  which  the  refuse  part  of  the  food  hardens 

and  is  not  easily  expelled  daily  from  the  large  intestine. 
Con  sump'tion  :  tuberculosis  of  the  lungs. 
Conta'gious  (con  ta'  jus)  :  catching. 
Cor'pus  cal  lo'sum  :  a  band   of  fibers  joining  the  two  halves  of  the 

cerebrum. 

Cor'pus  cle  (corpus  s7)  :  a  blood  cell. 
Cra'ni  al:  pertaining  to  the  cranium. 
Cra'nium  :  the  bones  surrounding  the  brain. 

Den'tine  (clen'tin)  :  the  hard  inner  part  of  the  teeth. 

Di'a  phragm  (tli'afrarri)  :  the  muscle  separating  the  cavity  of  the  chest 

from  that  of  the  abdomen. 
Diarrhe'a:  a  condition  in  which  the  bowel   excretions  contain  too 

much  liquid. 

Di  as'to  le  :  the  expanding  of  the  walls  of  the  heart. 
Di'et  :  a  course  of  food. 

Dis  in  fect'ant  :  a  substance  which  kills  germs. 
Dis  pen'sa  ry  :  a  place  where  the  poor  receive  free  medical  advice. 
Dys'entery:  inflammation  of  the  large  intestine  with  the  discharge 

of  some  blood. 
Dys  pep'si  a  :  a  failure  to  digest  the  food  properly. 

E  met'ic  :  an  agent  which  causes  vomiting. 

E  mul'sion  :  a  liquid  full  of  fine  particles  of  fat. 

Ep  i  the'li  um  :  the  layer  of  cells  covering  a  free  surface. 

E  soph'a  gus  (e  sofa  gus)  :  the  tube  taking  the  food  from  the  throat  to 

the  stomach. 
Eusta'chian  tube    (usta'kian):   the   tube   from   the   throat   to   the 

middle  ear. 
Ex  cre'ta  :  the  natural  discharges  from  the  body.     The  excreta  of  the 

bowels  are  called  feces. 

Fel'on:  an  inflammation  of  the  periosteum. 

Fem'o  ral  :  pertaining  to  the  femur. 

Fi'brin  :  a  proteid  in  coagulated  blood. 

Fi  brin'o  gen:  the  substance  in  the  blood  from  which  fibrin  is  formed. 


310      PRONUNCIATION    AND    EXPLANATION    OF    WORDS 

Fis'sure  (Jish'ur)  :  a  crevice  between  the  parts  of  an  organ. 

Fo'cus :  the  point  where  the  rays  of  light  meet  after  passing  through 

a  lens. 

Fol'li  cle  (fol'li  k'l)  :  a  little  pouch. 
For  mal'de  hyde :   a  germ-killing  gas.     The  gas    dissolved  in  water 

makes  formaldehyde  solution  or  formalin. 
For'malin:  a  solution  of  formaldehyde  gas  in  water.     It  is  a  much 

better  disinfectant  than  sulphur. 

Germs :  bacteria  and  also  tiny  animal  parasites. 

Gly'co  gen  :  animal  starch. 

Grippe  (grip)  :  a  contagious  disease  often  called  influenza. 

Hem  o  glo'bin  :  the  red  coloring  matter  of  red  blood  corpuscles. 

Hem'or  rhage  (hem' or  raj)  :  flow  of  blood  from  a  vessel. 

He  pat'ic  :  pertaining  to  the  liver. 

Hy'dro  gen :  a  gas  forming  two  thirds  of  water. 

Hygien'ic:  healthful. 

Il'i  ac :  pertaining  to  the  ilium  or  top  of  the  hip  bone. 

Im  bi  bi'tion  (im  hi  bish'un)  :  drinking  in. 

Im  niune' :  safe  from  disease. 

In  ci'sors :  front  teeth. 

In  flam  ma'tion :  the  condition  of  a  tissue  which  becomes  gorged  with 

blood  as  a  result  of  irritation,  usually  by  germs. 
In  oc  u  la'tion:  planting  the  germs  of  disease  in  the  body. 
In  vol'un  ta  ry  :  unable  to  control. 
I'ris :  the  colored  curtain  around  the  pupil  admitting  light  to  the  eye. 

Ju'gu  lar  vein  :  the  large  vein  in  the  neck. 

Lach'ry  mal  (lak'ri  mal)  :  the  name  of  the  tear  gland  and  its  duct. 
Lac'te  als  :  that  part  of  the  lymphatic  system  carrying  the  food  from 

the  intestines  to  the  thoracic  duct. 

Lar'ynx  (Winks*)  :  the  voice  box  at  the  top  of  the  windpipe. 
Lau'da  num :  a  solution  of  opium  in  alcohol. 
Lu'pus :  tuberculosis  of  the  skin. 
Lym  phat'ics :  small  vessels  for  returning  escaped  blood  to  the  veins 

in  the  neck,  and  carrying  food  from  the  intestines. 

Ma  la'ri  a :  a  disease  attended  with  chills  and  fever. 
Mas' sag  ing  (mas'saj  ing)  :   pressing  and  squeezing  any  part  of  the 
body  in  a  definite  way. 


PRONUNCIATION   AND   EXPLANATION   OF    WORDS      311 

Me  dul'la  ob  Ion  ga'ta :  the  stem  of  the  brain. 

Med'ul  la  ry  :  the  name  given  to  the  cavity  in  a  long  bone. 

Men  in  gi'tis :  an  inflammation  of  the  membranes  of  the  brain  or 
spinal  cord  caused  by  bacteria  such  as  germs. 

Mi'crobes  :  bacteria  and  other  ge  *ms. 

Mi'tral :  the  bicuspid  valve  in  the  heart  on  the  left  side. 

Mo' tor :  the  name  of  those  nerves  and  that  part  of  the  brain  control- 
ling the  muscles  of  the  body. 

Mu'cous  mem'brane :  that  which  lines  cavities  of  the  body  touched  by 
air. 

Mu'cus :  the  secretion  of  glands  in  the  mucous  membrane. 

Neu'ron :    a  nerve  cell  with  all  its  processes.    It  may  be  three  feet 

long. 

Nic'o  tine  (nicfo  tin)  :  the  poison  in  tobacco. 
Ni'tro  gen :  a  gas  forming  four  fifths  of  the  air. 
Ni  trog'e  nous  (ni  troj'e  nous)  :  said  of  foods  containing  much  proteid. 

Peas,  milk,  beans,  and  lean  meat  are  nitrogenous  foods. 

Oc  cip'i  tal  (ok  sip'i  tal)  :  name  of  a  bone  at  the  back  of  the  head. 

0  le  o  mar'ga  rine :    a  substitute  for  butter.     It  is  made  of  tallow  or 

lard  churned  with  milk  and  cotton-seed  oil. 

01  fac'to  ry :  pertaining  to  the  nose. 
Op'tic :  relating  to  the  eye. 

Or'bit  al   cav'i  ty :  the  cavity  for  the  eyeball. 

Or'gan :  any  part  of  the  body  having  a  definite  work  to  perform. 

Os  mo'sis :  the  oozing  of  a  liquid  through  a  membrane,  separating  it 

from  another  liquid. 

Ox  i  da'tion :  the  union  of  another  substance  with  oxygen. 
Ox'i  dize :  to  burn  or  unite  with  oxygen. 

Pa  pil'la :  a  little  elevation  on  the  skin  or  mucous  membrane. 

Pa  ral'y  sis  :  loss  of  power  to  move  or  feel  in  any  part.     It  is  caused 

by  injury  to  the  nerves,  cord,  or  brain. 
Par'a  sites :  animals  or  plants  that  feed  upon  other  living  animals  or 

plants  without  at  once  destroying  them. 

Par  e  gor'ic :  a  solution  of  water,  alcohol,  opium,  and  other  drugs. 
Pa  ri'e  tal :  a  bone  on  the  side  of  the  head. 
Pa  rot'id :  the  salivary  gland  below  the  ear. 
Pas'teur:  the  world's  greatest  benefactor.     He  discovered  the  cause 

and  prevention  of  disease. 


312      PRONUNCIATION   AND   EXPLANATION    OF   WORDS 

Pas  teur  i  za'tion :   heating  a  substance   to  about  160  degrees  for  a 

sufficient  time  to  kill  most  of  the  germs. 
Pat'ent  med'icines:   secret  preparations  advertised  to  cure  disease; 

most  of  them  are  worthless  and  many  are  very  harmful  to  health. 
Pep'sin :  a  digestive  ferment  made  rx  the  stomach. 
Pep'tone  :  a  digested  proteid. 
Per  i  car'di  um :  the  membrane  around  the  heart. 
Per  i  os'te  um :  the  membrane  around  the  bone. 
Per  i  stal'sis  :  the  movements  of  the  intestines. 
Per  i  to  ne'um :   the  delicate  membrane  lining  the  abdominal  cavity 

and  holding  the  organs  in  place. 
Per  i  to  ni'tis  :  inflammation  of  the  peritoneum. 
Pha  lan'ges :  the  bones  of  the  toes  and  fingers. 
Phar'ynx  (far'inks)  :  the  cavity  of  the  throat. 
Phthi'sis  (<Ai'.($w)  :  tuberculosis  of  the  lungs. 
Poste'rior:  behind. 

Pro'te  id :  a  substance  forming  most  of  the  dry  part  of  the  muscle. 
Pro'to  plasm:  the  chief  part  of  every  cell  in  plants  and  animals. 
Pto'ma  ine   (io'ma  in)  :   a  poison  developed   by  bacteria  in   stale   or 

canned  food. 
Pul'mo  na  ry  :  relating  to  the  lungs. 

Quack  doc'tors :  dishonest  persons  who  advertise  that  they  can  cure 
disease. 

Ret'i  na :  the  inner  coat  of  the  eye. 
/ 

Sa'crum :  the  bone  between  the  hips  ;  part  of  the  spinal  column. 

Sa  li'va :  the  slippery  fluid  used  to  moisten  the  food  in  the  mouth. 

Sal'i  va  ry  glands :  those  glands  in  the  head  forming  saliva. 

Scle  rot'ic  (side  rot'ic)  :  the  tough  outer  coat  of  the  eyeball. 

Scrof  u  la :  tuberculosis  of  the  lymph  glands. 

Se'rum :  the  clear  part  of  blood  clotted  in  a  cup  or  other  vessel. 

Ses'a  moid   bones :  small  bones  formed  about  the  joints  in  the  hands 

and  feet  and  at  the  knee. 
Spu'tum:  the  spit. 
Stim'u  lant :  that  which  hastens  the  action  of  an  organ  without  later 

slowing  it. 

Stim'u  lus :  an  impulse  or  excitement  carried  by  a  nerve  fiber. 
Sul'ci  (sul'si)  :  the  crevices  between  the  folds  on  the  surface  of  the 

brain. 


PRONUNCIATION   AND   EXPLANATION   OF    WORDS      313 

Syn  o'vi  a :  the  slippery  fluid  in  all  movable  joints. 
Sys'to  le :  the  contraction  or  squeezing  together  of  the  walls  of  the 
heart. 

Tac'tile  (tac'tiV)  :  pertaining  to  touch. 

Tho  rac'ic  (tho  ras'ik)  :  pertaining  to  the  thorax  or  chest. 

Tis'sue  (tish'v)  :  a  combination  of  cells  or  of  cells  and  fibers. 

Ton  si  li'tis :  a  contagious  disease  of  the  tonsils. 

Tra'che  a  (tra'ke  a)  :  the  windpipe. 

Trich  i  no'sis :  a  disease  caused  by  little  worms. 

Tym'panum:  the  middle  ear. 

U  re'a :  the  chief  solid  in  urine. 

Ure'ter :  one  of  the  two  tubes  from  the  kidneys  to  the  bladder. 

U'rine  (u'rin)  :  the  excretion  of  the  kidneys. 

U'vu  la :  ba  ;k  part  of  the  soft  palate. 

Vac'ci  nate :  to  prevent  disease  by  putting  into  the  body  through  the 
skin,  weakened  germs  or  the  excretions  of  the  germs  causing  that 
disease. 

Vac'cine :  smallpox  germs  weakened  by  growing  in  calves. 

Ver'te  bra:  one  of  the  bones  of  the  spinal  column. 

Vis'ce  ra :  the  internal  organs. 


INDEX 


Abdominal  cavity,  76. 

Absorption  of  food,  98-101. 

Accidents,  treatment  for,  294-305. 

Accommodation  of  eye,  249,  251. 

Acids,  29. 

Adam's  apple,  81,  134. 

Adenoids,  136,  146,  147. 

Adipose  tissue,  24. 

Adulteration  of  food,  42,  43,  62. 

Air,  composition  of,  151, 152;  impur- 
ities in,  153,  154;  in  relation  to 
health,  151-162. 

Air  cells,  138. 

Albumin,  23. 

Alcohol,  38,  51,  71,  72,  74,  75:  and 
crime,  170,  171 ;  and  disease,  131, 
168,  169,  269-271,  284;  danger 
from,  172,  173;  effect  on  blood, 
281 ;  on  bones,  201 ;  on  circulatory 
system,  130,  131;  on  heart,  120, 
168,  169;  on  heredity,  235,  236; 
on  kidneys,  178 ;  on  mind,  235  ;  on 
muscles,  211,  212 ;  on  nervous  sys- 
tem, 234-236 ;  on  respiratory  sys- 
tem, 148,  149 ;  on  sense  organs, 
256,  257;  on  skin,  189;  making 
of,  163-165  ;  poisoning  by,  295. 

Alcoholic  drink,  96,  M)4;  effect  on 
the  race,  163-174. 

Alcoholism,  260. 

Alimentary  canal,  76-85. 

Alkalies,  29. 

Ambulance,  289. 

Amceba,  107. 

Amoeboid  motion,  107. 

Anatomy,  meaning  of,  9. 

Ankle,  bones  of,  193,  194. 

Anthrax,  261. 

Antiseptic,  274. 

Antitoxin,  282. 

Aorta,  20,  116. 

Apoplexy,  130,  230. 

Appendicitis,  85,  267. 


Appendix,  vermiform,  77,  84. 
Aqueous  humor,  247,  248. 
Arsenic  poisoning,  304. 
Arteries,  118,  120,  121. 
Artery,  structure  of,  119. 
Articulation,  200. 
Artificial  breathing,  143,  144. 
Asthma,  144. 
Astigmatism,  252. 
Atlas,  192. 
Auricles,  116. 
Axis,  192. 
Axon,  219. 

Bacilli,  248. 

Bacteria,  16,  29,  46-52,  261,  263, 
279 ;  beneficial,  32,  33,  34,  51 ;  dis- 
ease-producing, 49-51 ;  in  air,  154; 
in  blood,  112;  in  breath,  156;  in 
milk,  13,  51,  54,  58-64 ;  in  mouth, 
48,  81  ;  in  soil,  48 ;  in  water,  48, 
266-268  ;  killing  of,  49,  280. 

Baldness,  183. 

Bathing,  187,  188. 

Beef  tea,  38. 

Beer,  72,  96,  97,  120,  130,  165,  168 

Bile,  97. 

Bladder,  20,  176. 

Bleeding,  129,  300. 

Blister,  180. 

Blood,  106-112;  corpuscles  of,  106- 
109;  plasma,  109;  poisoning  of, 
50,  264;  serum,  110. 

Blood  vessels,  118. 

Blushing,  223. 

Boils,  51,  268. 

Bone,  parts  of,  194,  195;  structure, 
196. 

Bones,  191-202;  development  of, 
196 ;  diseases  of,  199 ;  dislocation 
of,  201 ;  of  ear,  242. 

Brain,  215-218,  226-227;  exercise 
of,  231 ;  weight  of,  230,  231. 


315 


316 


INDEX 


Brandy,  165. 
Breakfast  foods,  43. 
Breathing,  138-145,  150. 
Bright 's  disease,  178. 
Broken  bones,  198. 
Bronchi,  137. 
Bronchioles,  137,  138. 
Bruises,  299. 

Bubonic  plague,  264,  267. 
Burns,  298. 
Butterine,  43. 
Buttermilk,  57. 

Caffein,  73. 

Cancer,  186. 

Capillaries,  108,  121,  122. 

Carbohydrates,  23,  26,  27,  36,  102. 

Carbolic  acid,  303. 

Carbon,  29,  34. 

Carbon  dioxide,  25,  27,  152,  153. 

Carpus,  194. 

Cartilage,  196. 

Casein,  24,  55,  56. 

Cataract,  256. 

Catarrh,  146. 

Cells,  14,  15,  16,  18,  21. 

Cerebellum,  216,  217,  226. 

Cerebrum,  216-^19,  226. 

Certified  milk,  61. 

Cheese,  37. 

Chicken  pox,  264,  277. 

Chocolate,  74. 

Cholera,  264. 

Cholera  infantum,  62,  269,  276. 

Choroid  coat,  247. 

Chyle,  97. 

Chyme,  93. 

Cigarettes,  70,  71,  148,  149,  233. 

Cilia,  16. 

Ciliary  muscle,  249,  251. 

Circulatory  system,  114-131. 

Clavicle,  192,  193. 

Clothing,  142,  188,  189. 

Coagulation,  24,  27. 

Cocaine,  71,  72. 

Coccyx,  191,  192. 

Cochlea,  241,  242. 

Cocoa,  74. 

Coffee,  73. 

Colds,  prevention  of,  188,  189. 

Color  blindness,  253. 

Complexion,  184,  185. 


Compound,  29. 

Condensed  milk,  58. 

Condiments,  37. 

Connective  tissue,  19. 

Constipation,  42. 

Consumption,  see  Tuberculosis 

Contagious  diseases,  259,  260,  264. 

Convulsions,  295. 

Cooking,  44. 

Corn,  180,  181. 

Cornea,  247,  249. 

Cranial  nerves,  217,  220,  221. 

Cranium,  191,  192. 

Cream,  57. 

Croup,  302. 

Cutis,  178. 

Cuts,  299. 

Dandruff,  184. 

Deafness,  243,  244. 

Decay,  51. 

Diabetes,  88. 

Diaphragm,  76,  77,  209. 

Diet,  40,  42. 

Digestion,  89 ;  intestinal,  96 ;  stom- 
ach, 92-94. 

Digestive  organs,  76-88. 

Diphtheria,  49,  51,  63,  64,  146,  264, 
272,  282,  283. 

Disease,  cause  of,  49-51,  260-262; 
contagious,  259-269 ;  infectious, 
260 ;  prevention  of,  272-293. 

Disinfectants,  273,  274. 

Disinfection,  273,  274,  275. 

Dislocation,  201. 

Dispensary,  289. 

Drinking  cup  and  disease,  260,  261, 
263,  285. 

Dropsy,  129. 

Drowning,  treatment  for,  144,  296, 
297. 

Duct,  85. 

Dysentery,  264,  276. 

Ear,  241-243 ;  care  of,  243. 

Ear  drum,  241. 

Eggs,  44,  53 ;  use  of,  for  tuberculosis, 

284. 

Emetics,  303. 
Emulsion,  25,  27. 
Epidermis,  178. 
Epiglottis,  134,  135. 


INDEX 


317 


Epilepsy,  295. 
Epithelium,  16,  18. 
Esophagus,  20,  82,  83. 
Eustachiaii  tube,  134. 
Excreta,  disposal  of,  279. 
Excretions,  177,  181. 
Excretorv  system,  175—187. 
Exercise,"  209,  210,  213,  231. 
Expiration,  139. 
Extensor  muscles,  206,  208. 
Eye,  246-253. 
Eyeball,  247. 

Eyes,  care  of,  253-255,  256 ;  testing, 
251. 

Fainting,  294. 

Farsightedness,  252. 

Fat,  cells  of,  16,  17,  103;  making  of, 
103,  104 ;  use  of,  25,  38. 

Fats,  22,  24,  25,  26,  37. 

Felon,  199. 

Femur,  192,  193,  194. 

Fermentation,  51,  163,  164. 

Ferments,  90,  93,  97,  110. 

Fibrin,  110. 

Fibula,  192,  193,  194. 

Filtration  of  water,  278. 

Fi At  aid,  13,  294. . 

Fits.  295. 

Flexor  muscles,  206,  208. 

Flies  and  disease,  268,  273,  274,  285. 

Focus,  248. 

Food,  35-45 ;  adulteration  of,  42-44, 
62 ;  cooking  of,  44 ;  digestion  of, 
90,  95 ;  preserving  of,  46,  52. 

Food  stuffs,  35. 

Formaldehyde,  13,^73,  275. 

Formalin,  13,  273. 

Fracture  of  bone,  198,  199. 

Fresh  air  and  disease,  161,  284. 

Frostbite,  298. 

Fruits,  42. 

Gall  bladder,  88. 

Ganglia,  221. 

Gastric  glands,  86,  87;  juice,  93. 

Germs,  47,  50,  61,  262,  264,  265;  of 
air.  154;  of  body,  280;  of  disease, 
49,  279,  281,  288;  of  milk,  262- 
268;  of  sewage,  "279;  of  water, 
266.  267,  270. 

Gland,  nature  of,  85. 


Glands,    digestive,    85-88,    87,    93  ; 

intestinal,     87;      sebaceous,     182; 

sweat,  179,  181;  thyroid,.  112. 
Glasses,  251,  252,  255. 
Gluten,  24. 
Glycogen,  102. 
Grippe,  264. 

Habits,  232. 

Hair,  183,  184. 

Haversian  canals,  195,  196. 

Headache,  95. 

Health,  rules  of,  291. 

Health  board,  230. 

Hearing,  243,  245. 

Heart,  114-120;  beating  off  118. 

Heat,  making  of,  38,  132. 

Heat  exhaustion,  296. 

Heating  rooms,  159. 

Hemoglobin,  106. 

Hemorrhage,  129. 

Heredity,  235,.  236. 

Hip  bone,  192,  193,  199. 

Hookworm  disease,  269,  273. 

Hospital,  289. 

Hydrogen,  30,  34. 

Hydrophobia,  13,  264,  269,  282,  288. 

Humerus,  192,  193,  194. 

Humors  of  eye,  247,  248. 

Immunity,  281. 

Incubation  period,  263,  264. 

Infectious  diseases,  49,  259-269. 

Inoculation,  285. 

Insects  and  health,  13,  268,  273,  285. 

Inspiration,  139. 

Intestines.  82,  84-87;  movements  of, 

97 ;   structure,  99. 
Intoxication,  295. 
Involuntary  muscles,  203,  204, 
Iris.  247,  248,  249. 
Iron,  23,  36,  106. 
Ivy  poisoning,  304,  305. 

Jenner,  286. 
Joint,  199,  200. 

Kidneys,  7,7,  175-177. 
Kneecap,  192. 

Lachrvmal  gland,  253. 
Lacteals,  99,  100,  125. 


318 


LNDEX 


Lard,  24. 
Larynx,  134-136. 
Lens,  248,  250. 
Leprosy,  264,  277. 
Ligament,  200. 
Light,  249. 
Liquors,  164,  165. 
Liver,  70,  77,  87,  88. 
Lockjaw,  259,  260,  264,  268. 
Lungs,  136-144;    diseases,  146;   ex- 
ercising, 145. 
Lymph,  109,  127. 
Lymphatics,  124-129. 
Lymph  glands,  126,  127. 
Lymph  nodes,  126,  127. 

Malar,  192. 

Malaria,  264,  269,  276. 

Malaria  germs,  155. 

Mandible,  192. 

Massaging,  210. 

Mastication,  91. 

Maxillary,  192. 

Measles,  264. 

Medulla  oblongata,  216,  226. 

Medullary  canal,  195. 

Membranous  croup,  146. 

Meningitis,  266. 

Metacarpals,  192. 

Metacarpus,  194. 

Metatarsals,  192,  193. 

Metatarsus,  194. 

Microbes,  46-53. 

Microscope,  15 

Milk,  54-66;  bulletins  on,  13;  care 
of,  60-61 ;  diseases  conveyed  by, 
54,  62-65,  268;  food  value,  55- 
57;  germs  in,  58-64;  pasteuriza- 
tion of,  65-66;  souring  of,  51, 
58. 

Milk  teeth,  78,  79. 

Mind,  231. 

Mineral  matter,  22,  23,  27. 

Molds,  46,  47,  48. 

Moles,  186. 

Morphine,  71,  72. 

Mosquitoes  and  disease, 

Motor  nerves,  220. 

Mouth,  77-82. 

Mucous  membrane,  77. 

Mucus.  77,  133. 

Mumps.  264,  277. 


Muscles,  202-213;   fibers  of,  18;   in- 
voluntary, 203,  204. 
Mushrooms,  poisonous,  302. 

Nails,  care  of,  185,  186. 

Narcotics,   68-75;    effect  on  bones, 

201 ;  on  sense  organs,  256-257. 
Nasal  passages,  133. 
Nearsightedness,  251. 
Nerve  cell,  16,  17,  218,  219,  225,  226 
Nerve  endings,  179,  238. 
Nerves,  214,  215,  220-222. 
Nerve  tissue,  19. 
Nervous  system,  214—245. 
Neuron,  16,  218,  219. 
Nicotine,  68-71. 
Nitrogen,  33,  151. 
Nucleus,  14. 

Occipital,  192. 
Oils,  24. 

Oleomargarine,  43. 
Opium,  71. 
Opsonins,  280. 
Orbital  cavity,  192,  246. 
Organ,  19. 
Osmosis,  100,  103. 
Oxidation.  31. 
Oxidized,  32. 
Oxygen,  31,  151. 

Pain,  239. 

Palate,  81,  134. 

Pancreas,  88. 

Paralysis,  130,  230. 

Parasites,  259. 

Paregoric,  71.        % 

Parotid  gland,  86. 

Pasteur,  260,  261,  286. 

Pasteurization,  65,  66. 

Patent  medicines,  71-73,  75,  166. 

Pepsin,  87. 

Peptones,  93. 

Pericardium,  114. 

Periosteum,  195,  202. 

Peristalsis,  97. 

Peritoneum,  76. 

Peritonitis,  264. 

Perspiration,  182. 

Phalanges,  192,  193,  194. 

Pharynx,  81,  82,  133,  134. 

Phthisis,  266. 


IXDEX 


319 


Physiology,  9,  10. 

Plasma,  106,  109. 

Pleura,  76,  138. 

Pleurisy,  138. 

Plexus,  221,  J-'-'. 

Pneumonia,  146,  169,  264,  272,  279. 

Poisoning  from  canned  food,  52. 

Poisonous  plants,  304. 

Poisons,  remedy  for,  303. 

Pons  Varolii,  217,  219. 

Portal  system,  100. 

Preserving  material,  12,  13. 

Proteids,  22,  23,  24,  36;   use  of,  38, 
102. 

Protoplasm,  14. 

Proximate  principles,  35. 

Pulmonary,  circulation,  127;     ves- 
sels, 116. 

Pulse,  119. 

Pupil,  248. 

Pus,  108. 

Quack  doctors,  244. 
Quarantine,  274. 

Radius,  192,  193.  194. 
Recti  muscles,  246. 
Reflex  action,  228,  229. 
Respiration,  140. 
Respiratory  system,  132—150. 
Respired  air,  156. 
Retina,  247,  248. 
Ribs,  193.  207. 
Rickets,  199. 
Ringworm,  48. 

Sacrum,  191. 

Saliva,  26,  90,  91,  92,  93. 

Salivary  glands,  86. 

Salt,  22,  36. 

Salts,  29. 

Sanatoria,  289 ;  for  tuberculosis,  199. 

Saponification,  25. 

Scapula,  193,  194. 

Scarlet  fever,  62,  64,  264,  275,  277.    ' 

Sciatic  nerve,  214,  222. 

Sclerotic  coat,  247. 

Scrofula,  49,  266. 

Sebaceous  glands,  182. 

Seeing,  250. 

Semicircular  canals,  241,  242. 

Semilunar  valves,  117,  118. 


Sense  organs,  237-258 ;  of  cold,  238 ; 

of  hearing,  241 ;   of  heat,  238 ;    of 

pain,   239;    of   pressure,   238;    of 

sight,  246 ;  of  smell,  239 ;  of  taste, 

240. 

Senses  of  skin,  238. 
Sensory  nerves,  220. 
Serous  membrane,  76. 
Serum  of  blood,  110. 
Sesamoid  bones,  194. 
Sewage,  13,  279. 
Sickness,  cause  of,  49-51,  260-262, 

from  milk,  54,  62-65 ;   prevention, 

of,  272-293. 

Sick  room,  care  of,  274,  275. 
Skeleton,  191-194. 
Skim  milk,  56. 
Skin,  structure  of,  178,  238 ;   use  of, 

180. 

Skull,  191-193. 
Sleep,  233. 

Sleeping  sickness,  264,  269. 
Smallpox,    264,    277,    282;     deaths 

from,  11,  287;  prevention  of,  285- 

288. 

Smell,  239. 
Snake  bite,  300. 
Soothing  sirups,  72. 
Souring  of  milk,  58. 
Spasms,  295. 
Spectacles,  251,  252. 
Spinal  column,  77,  192. 
Spinal  cord,  77,  214,  216,  219,  227- 

229. 

Spinal  nerves,  214,  220,  222. 
Spittoons  and  health,  285. 
Spleen,  88,  112. 
Spores,  47,  49. 
Sprain,  200,  201. 
Sputum,  263,  273,  274,  285. 
Starch,  24,  26,  36 ;  use  of,  38. 
Stimulants,  37,  68-75. 
Stings,  300. 
Stomach,  82-84,  87;  movements  of, 

93,  94. 

Strain,  200,  201. 
Suffocation,  297. 
Sugars,  24,  26 ;  use  of,  38. 
Sunstroke,  296. 

Sweat,  182 ;  glands  of,  179,  181,  388 
Sweeping  and  dusting,  160. 
Sweetbreads,  88. 


320 


INDEX 


Sympathetic  nerves,  215,  222,  223, 

228. 
Synovial     fluid,     202;      membrane, 

200. 

Systemic  circulation,  127. 
Systems,  20. 

Tallow,  24. 

Tarsals,  192. 

Tarsus,  194. 

Taste,  91,  240. 

Tea,  73. 

Tears,  253. 

Teeth,  78-82. 

Temperature  and  health,  160. 

Temporal  bone,  192. 

Tendons,  203,  207. 

Thoracic  cavity,  76. 

Thoracic  duct,  99,  100,  125. 

Thyroid  gland,  112. 

Tissues,  19. 

Tobacco,  68-71,  75;  effect  on  bones, 
201 ;  on  digestion,  92  ;  on  muscles, 
211;  on  nerves,  233,  234;  on  res- 
piratory organs,  147,  148 ;.  on 
sense  organs,  /256,  257. 

Tongue,  91,  134. 

Tonsil,  83,  134. 

Tonsilitis,  83. 

Touch,  238. 

Trachea,  20,  137. 

Trichinosis,  264,  267,  269. 

Tuberculosis,  11,  50,  63-65;  bulle- 
tins on,  13;  deaths  from,  272, 
282;  decrease  in  deaths  from,  12; 


disease  of,  146,  161,  169,  199,  265, 
266 ;  germs  of,  281 ;  prevention  of, 
208,  264-266,  278,  282-285  ;  symp- 
toms of,  284;  treatment  of,  58, 
284. 

Tumors,  187. 

Typhoid  fever,  12,  62,  63,  64,  264, 
272 ;  cause  of,  267,  268,  277 ;  pre- 
vention, 276,  278,  279. 

Ureter,  176. 

Vaccination,  286-288. 
Vaccines,  282. 
Valves  of  heart,  116. 
Veins,  122. 
Vena  cava,  116. 
Ventilation,  156-160. 
Villi,  97,  98,  99. 
Vocal  cords,  134,  135. 
Voice,  135,  136. 

Warts,  186. 

Water,  disease  from,  276,  277;  nitra- 
tion of,  278;  germs  in,  15,  266- 
268;  need  of,  12,22,50. 

Whisky,  72,  164,  165. 

White  blood  corpuscles,  107,  280, 
281. 

White  swelling,  199,  266. 

Whooping  cough,  264. 

Wine,  96. 

Wri*,  bones  of,  194. 

Yellow  fever,  264,  269. 


14 


XB  6551 


